[tests] Fix MediaWikiSiteTestCase.test_proofreadwiki

http://www.proofwiki.org is not reachable, use
http://proofwiki.org instead

Change-Id: Id44b03a8688c84c665c93581b659d73b5436d012

tests/site_detect_tests.py

@@ -119,7 +119,7 @@ def test_proofreadwiki(self):
         """Test detection of proofwiki.org site."""
         if os.getenv('GITHUB_ACTIONS'):
             self.skipTest('Skip test on github due to T331223')
-        self.assertSite('http://www.proofwiki.org/wiki/$1')
+        self.assertSite('http://proofwiki.org/wiki/$1')
 
     def test_non_standard_version_sites(self):
         """Test detection of non standard MediaWiki sites."""