refactor: Remove six.moves.StringIO import.

zerver/lib/test_fixtures.py

@@ -5,7 +5,7 @@ import hashlib
 import sys
 from typing import Any, List, Optional, Text
 from importlib import import_module
-from six.moves import cStringIO as StringIO
+from io import StringIO
 
 from django.db import connections, DEFAULT_DB_ALIAS
 from django.db.utils import OperationalError

zerver/tests/test_email_mirror.py

@@ -51,7 +51,7 @@ import ujson
 import mock
 import os
 import sys
-from six.moves import cStringIO as StringIO
+from io import StringIO
 from django.conf import settings
 
 from zerver.lib.str_utils import force_str

zerver/tests/test_type_debug.py

@@ -1,7 +1,7 @@
 
 import sys
 from unittest import TestCase
-from six.moves import cStringIO as StringIO
+from io import StringIO
 
 from zerver.lib.type_debug import print_types
 

zerver/tests/test_upload.py

@@ -36,7 +36,7 @@ from PIL import Image
 
 from boto.s3.connection import S3Connection
 from boto.s3.key import Key
-from six.moves import StringIO
+from io import StringIO
 import mock
 import os
 import io

zerver/worker/queue_processors.py

@@ -54,7 +54,7 @@ import datetime
 import logging
 import requests
 import ujson
-from six.moves import cStringIO as StringIO
+from io import StringIO
 import re
 import importlib