Update version to 7.31.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v7.30.0...47525abb7e6e3a1bf134963f8325583b1730de80

• Release notes:

### New scenarios and scenario updates

- !974 Update decomposition pipelines for multiple and single db scenarios

### Fixes

- !976 Explicitly require fileutils in logger

### Other changes (CI, backstage)

- !969 When a job needs not run, make it manual

• 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.