Fix flake8 type linting

Author: Nabellaleen

graphene_sqlalchemy/types.py

@@ -80,9 +80,9 @@ def construct_fields(model, registry, only_fields, exclude_fields):
 
 
 class SQLAlchemyObjectTypeOptions(ObjectTypeOptions):
-    model = None  # type: Model
+    model = None  # type: object
     registry = None  # type: Registry
-    connection = None  # type: Type[Connection]
+    connection = None  # type: Connection
     id = None  # type: str