gh-102627: Replace address pointing toward malicious web page (#102630)

* Replace known bad address pointing toward a malicious web page.

Co-authored-by: C.A.M. Gerlach <CAM.Gerlach@Gerlach.CAM>
Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

Doc/library/concurrent.futures.rst

@@ -202,7 +202,7 @@ ThreadPoolExecutor Example
            'http://www.cnn.com/',
            'http://europe.wsj.com/',
            'http://www.bbc.co.uk/',
-           'http://some-made-up-domain.com/']
+           'http://nonexistant-subdomain.python.org/']
 
    # Retrieve a single page and report the URL and contents
    def load_url(url, timeout):