Bump version 7.9.3

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v7.9.2...7b7be2bb572ac5c39c618ff4cb1724db3334b91e

• Release notes:

Other changes (CI, backstage)

Bump http & rake gem versions for Ruby 3 support.

• 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.