GH-93112: Fix missing ResourceDenied import in test_urllib2net (#93113)

The code was moved out of test.support in
311110abcd (GH-20812), thus making
ResourceDenied undefined.

Lib/test/test_urllib2net.py

@@ -3,6 +3,7 @@ import unittest
 from test import support
 from test.support import os_helper
 from test.support import socket_helper
+from test.support import ResourceDenied
 from test.test_urllib2 import sanepathname2url
 
 import os