Actually suppress warnings in test_at_least_import_untested_modules

inside the catch_warnings context manager.

Lib/test/test_sundry.py

@@ -9,6 +9,7 @@ import warnings
 class TestUntestedModules(unittest.TestCase):
     def test_at_least_import_untested_modules(self):
         with warnings.catch_warnings():
+            warnings.simplefilter("ignore")
             import CGIHTTPServer
             import aifc
             import audiodev