osx: update bugzilla link in readme

contrib/macosx/Readme.html

@@ -32,6 +32,6 b''
 <p class="p1"><b>Reporting problems</b></p>
 <p class="p2"><br></p>
 <p class="p3">If you run into any problems, please file a bug online:</p>
-<p class="p3"><a href="http://bz.selenic.com/">http://bz.selenic.com/</a></p>
+<p class="p3"><a href="https://bz.mercurial-scm.org/">https://bz.mercurial-scm.org/</a></p>
 </body>
 </html>