reorganize imports with ruff

sas/migrations/0001_initial.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
-from django.db import migrations, models
+from django.db import migrations
 
 
 class Migration(migrations.Migration):

sas/migrations/0002_auto_20161119_1241.py

@@ -1,9 +1,9 @@
 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
-from django.db import migrations, models
-from django.conf import settings
 import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
 
 
 class Migration(migrations.Migration):