gh-135056: Fix socket closing in test_extra_response_headers_arg

Author: aisipos

Lib/test/test_httpservers.py

@@ -1558,6 +1558,7 @@ def test_extra_response_headers_arg(self, _, mock_make_server):
         # the spied call args, then calling _make_server with them.
         args, kwargs = mock_make_server.call_args
         httpd = server._make_server(*args, **kwargs)
+        self.addCleanup(httpd.server_close)
 
         # Ensure the RequestHandler class is passed the correct response
         # headers