Run bulk_update on Right instances and not Right IDs

arkindex/process/migrations/0038_remove_repository_worker_rights.py

@@ -27,7 +27,7 @@ def migrate_repository_rights(apps, schema):
             if right and right.level < repo_right.level:
                 # If the current access level < the one defined at repository level, update it
                 right.level = repo_right.level
-                to_update.append(right.id)
+                to_update.append(right)
             # Otherwise create a new right on the worker for this user or group
             elif not right:
                 to_create.append(