Release version 1.12.0

• Diff: https://gitlab.com/gitlab-org/gitlab-triage/compare/v1.11.0...3e9dd42ce6951aff696edbd7df744dd8fed2334c

• Release notes:

Bump major version because this contains bug fixes which will break workaround for the bug.

### Fixes

- !174 Fix label checks when there's a space in the name
- !175 Use `%20` instead of `+` in the URL

### Other changes (tooling, technical debt)

- !171 Make Resources classes inherit from SimpleDelegator

• Checklist before merging:

  • Diff link is up-to-date.
  • Based on the diff, lib/gitlab/triage/version.rb is updated, according to SemVer.
  • Release notes are accurate.

• Checklist after merging:

  • Update the release notes for the newly created tag.