Don't cast account_id to integer to support other type of primary keys

src/django_paddle_billing/models.py

@@ -547,7 +547,7 @@ def from_paddle_data(cls, data, occurred_at=None) -> tuple["Subscription | None"
             pass
 
         if account_id is not None:
-            if not get_account_model().objects.filter(pk=int(account_id)).exists():
+            if not get_account_model().objects.filter(pk=account_id).exists():
                 error = f"Subscription: Account with id: {account_id} does not exist"
                 return None, False, error