Silly linting change

import ordering matters

tests/test_relations_pk.py

@@ -6,8 +6,8 @@ from django.utils import six
 from rest_framework import serializers
 from tests.models import (
     ForeignKeySource, ForeignKeyTarget, ManyToManySource, ManyToManyTarget,
-    NullableForeignKeySource, NullableOneToOneSource, OneToOnePKSource,
-    NullableUUIDForeignKeySource, OneToOneTarget, UUIDForeignKeyTarget
+    NullableForeignKeySource, NullableOneToOneSource, NullableUUIDForeignKeySource,
+    OneToOnePKSource, OneToOneTarget, UUIDForeignKeyTarget
 )