Remove unnecessary select for removing an auth code grant

Author: q0w

oauth2_provider/oauth2_validators.py

@@ -322,10 +322,10 @@ def invalidate_authorization_code(self, client_id, code, request, *args, **kwarg
 
         :raises: InvalidGrantError if the grant does not exist.
         """
-        try:
-            grant = Grant.objects.get(code=code, application=request.client)
-            grant.delete()
-        except Grant.DoesNotExist:
+        deleted_grant_count = Grant.objects.filter(
+            code=code, application=request.client
+        ).delete()
+        if not deleted_grant_count:
             raise errors.InvalidGrantError(request=request)
 
     def validate_client_id(self, client_id, request, *args, **kwargs):