bpo-40275: Use new test.support helper submodules in tests (GH-21315)

diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py
index 4bf5d39..93ca6b9 100644
--- a/Lib/test/test_wsgiref.py
+++ b/Lib/test/test_wsgiref.py
@@ -1,6 +1,7 @@
 from unittest import mock
 from test import support
 from test.support import socket_helper
+from test.support import warnings_helper
 from test.test_httpservers import NoLogRequestHandler
 from unittest import TestCase
 from wsgiref.util import setup_testing_defaults
@@ -339,7 +340,7 @@
         util.setup_testing_defaults(kw)
         self.assertEqual(util.request_uri(kw,query),uri)
 
-    @support.ignore_warnings(category=DeprecationWarning)
+    @warnings_helper.ignore_warnings(category=DeprecationWarning)
     def checkFW(self,text,size,match):
 
         def make_it(text=text,size=size):