moderation: handle system actions for the community flow

* Fixes a bug occuring when the moderation handlers run for community
  updates during system actions (e.g. when an admin accepts a
  subcommunity inclusion request).

site/zenodo_rdm/moderation/handlers.py

@@ -231,6 +231,9 @@ def __init__(self):
 
     def _run(self, identity, record, uow):
         """Run the moderation scoring."""
+        # Skip moderation for system actions (e.g. subcommunity inclusion actions)
+        if identity == system_identity:
+            return
         user = UserAggregate.get_record(identity.id)
 
         # Perform the moderation checks asynchronously for verified users