Fixed a small collection of flake8 violations that had snuck in

tests/model_forms/tests.py

@@ -1297,7 +1297,7 @@ class ModelFormBasicTests(TestCase):
         self.assertEqual(Category.objects.get(id=cat.id).name, 'Third')
 
     def test_runtime_choicefield_populated(self):
-        self.maxDiff=None
+        self.maxDiff = None
         # Here, we demonstrate that choices for a ForeignKey ChoiceField are determined
         # at runtime, based on the data in the database when the form is displayed, not
         # the data in the database when the form is instantiated.
@@ -1988,6 +1988,7 @@ class FileAndImageFieldTests(TestCase):
         self.assertEqual(instance.image.name, 'foo/test4.png')
         instance.delete()
 
+
 class ModelOtherFieldTests(TestCase):
     def test_big_integer_field(self):
         bif = BigIntForm({'biggie': '-9223372036854775808'})