Bump sidekiq-unique-jobs from 6.0.13 to 6.0.15 (#12102)

Bumps [sidekiq-unique-jobs](https://github.com/mhenrixon/sidekiq-unique-jobs) from 6.0.13 to 6.0.15.
- [Release notes](https://github.com/mhenrixon/sidekiq-unique-jobs/releases)
- [Changelog](https://github.com/mhenrixon/sidekiq-unique-jobs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mhenrixon/sidekiq-unique-jobs/compare/v6.0.13...v6.0.15)

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

Gemfile.lock

@@ -462,7 +462,7 @@ GEM
     rack-attack (6.1.0)
       rack (>= 1.0, < 3)
     rack-cors (1.0.3)
-    rack-protection (2.0.5)
+    rack-protection (2.0.7)
       rack
     rack-proxy (0.6.5)
       rack
@@ -590,7 +590,7 @@ GEM
       rufus-scheduler (~> 3.2)
       sidekiq (>= 3)
       tilt (>= 1.4.0)
-    sidekiq-unique-jobs (6.0.13)
+    sidekiq-unique-jobs (6.0.15)
       concurrent-ruby (~> 1.0, >= 1.0.5)
       sidekiq (>= 4.0, < 7.0)
       thor (~> 0)