Add rake job to list MRs for next patch release

What does this MR do and why?

This adds a new rake task release:pending_backports that will post a slack message listing the MRs that have been merged in stable branches and will be included in the next patch release. The slack message will return the information in markdown format so it can easily be copy/pasted into the blog post. The job log output will also print this markdown output (see terminal output below).

The main motivation behind this feature is we need a way to get a list of non-security bug fixes that will be included during our security patch releases so we can add them to the blog post. However, this is set up in a general way, so it can also be used when planning a regular patch release.

gitlab-com/chatops!367 (merged) will follow this MR to add chatops support for running this task with /chatops run release pending_backports

Related to gitlab-com/gl-infra/delivery#2934 (closed)

Local testing

Terminal output

~ CHAT_CHANNEL=<channel_id> SLACK_CHATOPS_URL=<slack_url> RELEASE_BOT_PRODUCTION_TOKEN=<personal_access_token> RELEASE_BOT_VERSION_TOKEN=<version_token> bundle exec rake release:pending_backports
2023-04-11 13:37:49.907226 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:49 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fbuild%2FCNG/repository/compare" -
2023-04-11 13:37:49.907355 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/build/CNG, :tag=>"v15.10.2", :branch=>"15-10-stable", :commits=>0}
2023-04-11 13:37:49.907365 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/build/CNG, :version=>"15.10.2", :count=>0}
2023-04-11 13:37:50.155289 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:50 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitaly/repository/compare" -
2023-04-11 13:37:50.155355 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitaly, :tag=>"v15.10.2", :branch=>"15-10-stable", :commits=>0}
2023-04-11 13:37:50.155364 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitaly, :version=>"15.10.2", :count=>0}
2023-04-11 13:37:50.463664 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:50 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/compare" -
2023-04-11 13:37:50.463934 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitlab, :tag=>"v15.10.2-ee", :branch=>"15-10-stable-ee", :commits=>4}
2023-04-11 13:37:50.947027 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:50 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/commits/b27858b6e4f1d796b61eddb21fbb7dff41067aad/merge_requests" -
2023-04-11 13:37:51.476117 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:51 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/commits/ab8b3f78bba8cddaefc295a0eedda175e9da4ff6/merge_requests" -
2023-04-11 13:37:52.042456 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:52 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/commits/8efa99f715c9ad3419b1c0fa5bc0917b64b4d4ef/merge_requests" -
2023-04-11 13:37:52.591105 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:52 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/commits/c7c5131cf62e307cf7a7e88efbbdc2638354eaa5/merge_requests" -
2023-04-11 13:37:52.591322 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitlab, :version=>"15.10.2", :count=>4}
2023-04-11 13:37:52.833199 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:52 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab-pages/repository/compare" -
2023-04-11 13:37:52.833269 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitlab-pages, :tag=>"v15.10.2", :branch=>"15-10-stable", :commits=>0}
2023-04-11 13:37:52.833276 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitlab-pages, :version=>"15.10.2", :count=>0}
2023-04-11 13:37:53.115019 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:53 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fomnibus-gitlab/repository/compare" -
2023-04-11 13:37:53.115149 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/omnibus-gitlab, :tag=>"15.10.2+ee.0", :branch=>"15-10-stable", :commits=>1}
2023-04-11 13:37:53.568307 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:53 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fomnibus-gitlab/repository/commits/51a37551b0c22bfe203b0637734ca23c1e755464/merge_requests" -
2023-04-11 13:37:53.568485 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/omnibus-gitlab, :version=>"15.10.2", :count=>1}
2023-04-11 13:37:53.892297 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:53 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fbuild%2FCNG/repository/compare" -
2023-04-11 13:37:53.892410 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/build/CNG, :tag=>"v15.9.4", :branch=>"15-9-stable", :commits=>1}
2023-04-11 13:37:54.244870 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:54 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fbuild%2FCNG/repository/commits/e1ca349f4396c8a3e0c370ee72a39fdbcadc756f/merge_requests" 2
2023-04-11 13:37:54.244924 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/build/CNG, :version=>"15.9.4", :count=>0}
2023-04-11 13:37:54.502118 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:54 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitaly/repository/compare" -
2023-04-11 13:37:54.502213 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitaly, :tag=>"v15.9.4", :branch=>"15-9-stable", :commits=>1}
2023-04-11 13:37:54.833837 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:54 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitaly/repository/commits/d6384e179a1f6310905a9f0ced4359753e4d8c5b/merge_requests" 2
2023-04-11 13:37:54.833886 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitaly, :version=>"15.9.4", :count=>0}
2023-04-11 13:37:55.106368 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:55 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/compare" -
2023-04-11 13:37:55.106471 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitlab, :tag=>"v15.9.4-ee", :branch=>"15-9-stable-ee", :commits=>1}
2023-04-11 13:37:55.446488 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:55 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/commits/2d0291d1ff5ecf5ef3e973d2da73e445deaef724/merge_requests" 2
2023-04-11 13:37:55.446539 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitlab, :version=>"15.9.4", :count=>0}
2023-04-11 13:37:57.022845 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:57 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab-pages/repository/compare" -
2023-04-11 13:37:57.022938 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitlab-pages, :tag=>"v15.9.4", :branch=>"15-9-stable", :commits=>1}
2023-04-11 13:37:57.409179 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:57 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab-pages/repository/commits/0f55954deadb8ae9f0031f41373461c2f324b0d8/merge_requests" 2
2023-04-11 13:37:57.409230 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitlab-pages, :version=>"15.9.4", :count=>0}
2023-04-11 13:37:57.714194 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:57 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fomnibus-gitlab/repository/compare" -
2023-04-11 13:37:57.714296 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/omnibus-gitlab, :tag=>"15.9.4+ee.0", :branch=>"15-9-stable", :commits=>1}
2023-04-11 13:37:58.094313 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:58 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fomnibus-gitlab/repository/commits/3163530ead8efa575bda6ea0b52e87624564894f/merge_requests" 2
2023-04-11 13:37:58.094363 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/omnibus-gitlab, :version=>"15.9.4", :count=>0}
2023-04-11 13:37:58.374005 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:58 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fbuild%2FCNG/repository/compare" -
2023-04-11 13:37:58.374130 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/build/CNG, :tag=>"v15.8.5", :branch=>"15-8-stable", :commits=>1}
2023-04-11 13:37:58.732541 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:58 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fbuild%2FCNG/repository/commits/de0203325714abd3f6cfe00ee7954ef00fcb031c/merge_requests" 2
2023-04-11 13:37:58.732600 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/build/CNG, :version=>"15.8.5", :count=>0}
2023-04-11 13:37:59.147323 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:59 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitaly/repository/compare" -
2023-04-11 13:37:59.147426 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitaly, :tag=>"v15.8.5", :branch=>"15-8-stable", :commits=>1}
2023-04-11 13:37:59.478925 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:59 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitaly/repository/commits/ee65efe8c4ac4fff9a79808eb1eb32492d428c8b/merge_requests" 2
2023-04-11 13:37:59.478974 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitaly, :version=>"15.8.5", :count=>0}
2023-04-11 13:37:59.764753 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:37:59 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/compare" -
2023-04-11 13:37:59.764864 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitlab, :tag=>"v15.8.5-ee", :branch=>"15-8-stable-ee", :commits=>1}
2023-04-11 13:38:00.094289 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:38:00 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab/repository/commits/ceeae893d0b0dfc61feb11fe4ec74bb3397c2afc/merge_requests" 2
2023-04-11 13:38:00.094343 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitlab, :version=>"15.8.5", :count=>0}
2023-04-11 13:38:00.423650 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:38:00 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab-pages/repository/compare" -
2023-04-11 13:38:00.423749 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/gitlab-pages, :tag=>"v15.8.5", :branch=>"15-8-stable", :commits=>1}
2023-04-11 13:38:00.719605 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:38:00 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fgitlab-pages/repository/commits/a3132f136d0873134ab830969303c456a720f246/merge_requests" 2
2023-04-11 13:38:00.719656 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/gitlab-pages, :version=>"15.8.5", :count=>0}
2023-04-11 13:38:00.982244 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:38:00 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fomnibus-gitlab/repository/compare" -
2023-04-11 13:38:00.982346 I ReleaseTools::PatchRelease::UnreleasedCommits -- Fetching unreleased commits -- {:project=>gitlab-org/omnibus-gitlab, :tag=>"15.8.5+ee.0", :branch=>"15-8-stable", :commits=>1}
2023-04-11 13:38:01.330546 D ReleaseTools::GitlabClient -- [HTTParty] [2023-04-11 13:38:01 -0600] 200 "GET https://gitlab.com/api/v4/projects/gitlab-org%2Fomnibus-gitlab/repository/commits/3d75f9745f50aecfa34b92f865edcdacb4d6f1be/merge_requests" 2
2023-04-11 13:38:01.330600 I ReleaseTools::PatchRelease::UnreleasedMergeRequests -- Fetched unreleased merge requests -- {:project=>gitlab-org/omnibus-gitlab, :version=>"15.8.5", :count=>0}
2023-04-11 13:38:01.330624 I ReleaseTools -- Notifying 15.10.3, 15.9.5, 15.8.6 backports on slack.
2023-04-11 13:38:01.695193 I ReleaseTools::Slack::PatchReleaseMergeRequestsNotification -- *Merge requests merged into upcoming patch versions*
2023-04-11 13:38:01.695197 I ReleaseTools::Slack::PatchReleaseMergeRequestsNotification --
### 15.10.3

* [Change the order of vulnerability creation](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/116851)
* [Resolve ambiguous references for archive metadata (backport)](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/116824)
* [Verify deploy keys settings for protected tags (backport)](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/116952)
* [Always run package-and-test notify-failure job](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/116596)
* [[15.10 Backport] Fix suggested_reviewers runs when rails is disabled](https://gitlab.com/gitlab-org/omnibus-gitlab/-/merge_requests/6794)

Author Check-list

• [-] Has documentation been updated?