Fix flake8 violations: remove extra blank lines and trailing whitespace

tests/test_authtoken.py

@@ -50,8 +50,6 @@ class AuthTokenTests(TestCase):
         self.user.save()
         assert AuthTokenSerializer(data=data).is_valid()
 
-
-
     def test_token_creation_collision_raises_integrity_error(self):
         """
         Verify that creating a token with an existing key raises IntegrityError.