Fix linting.

Author: Andrew Bettke

graphene_django/types.py

@@ -134,7 +134,7 @@ def is_type_of(cls, root, info):
             model = root._meta.model
         else:
             model = root._meta.model._meta.concrete_model
-            
+
         return model == cls._meta.model
 
     @classmethod