Update version to 9.0.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v8.15.3...32cc24e3ea5e1908baa0a4a9771a0e9705a15781

• Release notes:

### Breaking change

- !1125 Set license mode via GitLab component only

• 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:

  • Update the release notes for the newly created tag.