Resolve "Review permissions"

Closes #83 (closed)

aleksis/apps/chronos/util/predicates.py

@@ -13,7 +13,7 @@ def has_timetable_perm(user: User, obj: Model) -> bool:
     """Predicate which checks whether the user is allowed to access the requested timetable."""
     if type(obj) is Group:
         return (
-            user.person.member_of.filter(id=obj.id).exists()
+            obj in user.person.member_of.all()
             or user.person.primary_group == obj
             or user.person.owner_of.filter(id=obj.id).exists()
             or has_global_perm("chronos.view_all_group_timetables")(user)