gevent.org test: Normalize even when using system resolver.

20230707: Round-robin DNS on GitHub actions is constantly producing different addresses.

src/gevent/tests/test__socket_dns.py

@@ -657,11 +657,12 @@ class TestGeventOrg(TestCase):
     # trying www.gevent.org which is a CNAME to readthedocs.org then worked, but it became
     # an alias for python-gevent.readthedocs.org, which is an alias for readthedocs.io,
     # and which also has multiple addresses. So we run the resolver twice to try to get
-    # the different answers, if needed.
+    # the different answers, if needed. Even then it's not enough, so
+    # we normalize the two addresses we get to a single one.
     HOSTNAME = 'www.gevent.org'
 
 
-    if RESOLVER_NOT_SYSTEM:
+
     def _normalize_result_gethostbyname(self, result):
         if result == '104.17.33.82':
             result = '104.17.32.82'