Fix predicate

aleksis/apps/paweljong/predicates.py

@@ -43,4 +43,4 @@ def is_event_published(user: User, obj: EventRegistration) -> bool:
 @predicate
 def is_participant(user: User, obj: Event) -> bool:
     """Predicate which checks if the user is member of the event."""
-    return user in obj.linked_group.members.all()
+    return user.person in obj.linked_group.members.all()