Fix CI: Switch to original redmine_sidekiq repository with Rails 6+ compatibility

Co-authored-by: PowerKiKi <[email protected]>

Author: Copilot

.github/workflows/test.yml

@@ -71,10 +71,7 @@ jobs:
       - name: Checkout redmine_sidekiq
         uses: actions/checkout@v3
         with:
-          # TODO Switch back to the original repo, once https://github.com/ogom/redmine_sidekiq/pull/16 is released
-          # repository: ogom/redmine_sidekiq
-          repository: dosyfier/redmine_sidekiq
-          ref: fix-rails-6
+          repository: ogom/redmine_sidekiq
           path: redmine/plugins/redmine_sidekiq
 
       - name: Checkout gitolite