WIP: Integrate releasing runners

TODO

Reference:

• gitlab-runner#2870 (closed)

• Update issues template

  • Monthly: $1683570
  • Patch
  • Security

• Update scripts

  • Release script following https://gitlab.com/gitlab-org/gitlab-runner/tree/master/docs/release_process#stable-release-timeline
  • Update CHANGELOG using https://gitlab.com/gitlab-org/gitlab-runner/blob/master/scripts/prepare-changelog-entries.rb