Bump version to 7.7.1

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v7.7.0...211317d2521448ff89bb97df3a13def475a39009

• Release notes:

### Fixes

- !739 Encode the query string in the issue search link.

• 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.