Re-aim the "about the benchmarks" link

Benchmarks are now at github.com/python/performance, not hg.python.org/benchmarks

Author: zware

speed_python/templates/about.html

@@ -78,7 +78,7 @@ <h4>Resources</h4>
 </ul>
 
 <h3>About the benchmarks</h3>
-<p>The code can be found <a href="https://hg.python.org/benchmarks">here</a>.</p>
+<p>The code can be found <a href="https://github.com/python/performance">here</a>.</p>
 <h3>About Python</h3>
 <p>Python is a programming language that lets you work quickly and integrate systems more effectively.</p>
 <p>Main website: <a href="https://python.org/">python.org</a></p>