fix six imports

graphene_django/debug/sql/tracking.py

@@ -5,7 +5,7 @@ import json
 from threading import local
 from time import time
 
-from django.utils import six
+import six
 from django.utils.encoding import force_text
 
 from .types import DjangoDebugSQL

graphene_django/settings.py

@@ -13,9 +13,9 @@ back to the defaults.
 """
 from __future__ import unicode_literals
 
+import six
 from django.conf import settings
 from django.test.signals import setting_changed
-from django.utils import six
 
 try:
     import importlib  # Available in Python 3.1+

graphene_django/utils/utils.py

@@ -1,8 +1,8 @@
 import inspect
 
+import six
 from django.db import models
 from django.db.models.manager import Manager
-from django.utils import six
 from django.utils.encoding import force_text
 from django.utils.functional import Promise