[3.13] gh-148909: Fix broken author attribution URL in 'The Python 2.3 Method Resolution Order' doc (GH-149092) (#152573)

(cherry picked from commit 7aae0e5)

Co-authored-by: Ivy Xu <fakeshadow1337@gmail.com>

Author: miss-islington

Doc/howto/mro.rst

@@ -10,7 +10,7 @@ The Python 2.3 Method Resolution Order
    The Method Resolution Order discussed here was *introduced* in Python 2.3,
    but it is still used in later versions -- including Python 3.
 
-By `Michele Simionato <https://www.phyast.pitt.edu/~micheles/>`__.
+By `Michele Simionato <https://github.com/micheles>`__.
 
 :Abstract: