Bump Version 6.1.1

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v6.1.0...b439108ad15998dfa8d3f98a23ecedced1b56547

• Release notes:

### Other changes (CI, backstage)

- !513 Add CACHE_NAMESPACE_NAME env var

• Checklist before merging:

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

• Checklist after merging:

  • Create a tag for the new release version.