Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `.github/dependabot.yml`:
  Upstream made changes while we have dropped this file.
  Keep the file deleted.
- `.prettierignore`:
  Upstream made changes at the end of the file, where we
  had our extra lines.
  Just moved our extra lines back at the end.
- `app/serializers/initial_state_serializer.rb`:
  Upstream code style changes.
  Applied them.
- `app/services/backup_service.rb`:
  Upstream code style changes.
  Applied them.

app/serializers/rest/instance_serializer.rb

@@ -96,9 +96,7 @@ class REST::InstanceSerializer < ActiveModel::Serializer
   end
 
   def registrations_message
-    if Setting.closed_registrations_message.present?
-      markdown.render(Setting.closed_registrations_message)
-    end
+    markdown.render(Setting.closed_registrations_message) if Setting.closed_registrations_message.present?
   end
 
   def markdown