Bump version to 3.4.2

Diff

https://gitlab.com/gitlab-org/ruby/gems/gitlab-dangerfiles/compare/v3.4.1...bump-version-to-3.4.2

Checklist

• Diff link is up-to-date.
• Check the release notes: https://gitlab.com/api/v4/projects/gitlab-org%2Fruby%2Fgems%2Fgitlab-dangerfiles/repository/changelog?version=3.4.2
• Based on the diff and the release notes, version.rb is updated, according to SemVer.