Bump version to 4.14.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v4.13.0...2e7b1bb9ac0e512bc11d2e843bc54256d42489c8

• Release notes:

### Other changes (CI, backstage)

- !340 Pass through the CI_SERVER_HOST and CI_SERVER_PERSONAL_ACCESS_TOKEN env var.
- !341 Add documentation for CI_SERVER_PERSONAL_ACCESS_TOKEN

• 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.