refactor(content_management): add type to DeletionEvent in archived headlines

- Specify generic type for DeletionEvent in _DeletionServiceStatusChanged event

Author: fulleni

lib/content_management/bloc/archived_headlines/archived_headlines_event.dart

@@ -65,7 +65,7 @@ final class ClearRestoredHeadline extends ArchivedHeadlinesEvent {
 final class _DeletionServiceStatusChanged extends ArchivedHeadlinesEvent {
   const _DeletionServiceStatusChanged(this.event);
 
-  final DeletionEvent event;
+  final DeletionEvent<dynamic> event;
 
   @override
   List<Object?> get props => [event];