Fixed event create (#446)

Author: michalmasrna1

competition/models.py

@@ -203,7 +203,7 @@ def can_user_modify(self, user):
 
     @classmethod
     def can_user_create(cls, user: User, data: dict) -> bool:
-        competition = Competition.objects.get(pk=data['competition'])
+        competition = Competition.objects.get(pk=data['competition'].id)
         return competition.can_user_modify(user)
 
     def can_user_participate(self, user):