Bump version to 7.1.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v7.0.5...ad1a4888d0d2af4aecfeb736fd59174f3f3444a4

• Release notes:

### Fixes

- !690 Stub Scenario.attributes.include?.
- !691 Move stub Runtime::Scenario.attributes.include? to before block.

### Other changes (CI, backstage)

- !688 Add tagging to object_storage and packages.
- !687 Set initial root password by default.

• 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.