[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

app_helper/base_test.py

@@ -3,6 +3,7 @@
 from collections import OrderedDict
 from contextlib import contextmanager
 from copy import deepcopy
+from io import StringIO
 from tempfile import mkdtemp
 from unittest.mock import patch
 
@@ -11,7 +12,6 @@
 from django.http import SimpleCookie
 from django.test import RequestFactory, TestCase, TransactionTestCase
 from django.utils.functional import SimpleLazyObject
-from io import StringIO
 
 from .utils import UserLoginContext, create_user, get_user_model, reload_urls, temp_dir