Bump sidekiq-unique-jobs from 7.1.19 to 7.1.21 (mastodon#18085)

Bumps [sidekiq-unique-jobs](https://github.com/mhenrixon/sidekiq-unique-jobs) from 7.1.19 to 7.1.21.
- [Release notes](https://github.com/mhenrixon/sidekiq-unique-jobs/releases)
- [Changelog](https://github.com/mhenrixon/sidekiq-unique-jobs/blob/main/CHANGELOG.md)
- [Commits](mhenrixon/sidekiq-unique-jobs@v7.1.19...v7.1.21)

---
updated-dependencies:
- dependency-name: sidekiq-unique-jobs
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -617,7 +617,7 @@ GEM
       sidekiq (>= 3)
       thwait
       tilt (>= 1.4.0)
-    sidekiq-unique-jobs (7.1.19)
+    sidekiq-unique-jobs (7.1.21)
       brpoplpush-redis_script (> 0.1.1, <= 2.0.0)
       concurrent-ruby (~> 1.0, >= 1.0.5)
       sidekiq (>= 5.0, < 8.0)