stages/invitation: fix linting

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

authentik/stages/invitation/tests.py

@@ -144,7 +144,7 @@ class TestInvitationsAPI(APITestCase):
         response = self.client.post(
             reverse("authentik_api:invitation-list"),
             {"identifier": "test-token", "fixed_data": {}},
-            format="json"
+            format="json",
         )
         self.assertEqual(response.status_code, 201)
         self.assertEqual(Invitation.objects.first().created_by, self.user)