Update CoC link to PSF policies site (#19)

Author: hugovk

CODE_OF_CONDUCT.md

@@ -22,4 +22,4 @@ For any report that involves the above admins/moderators, email
 conduct-wg@python.org instead.
 
 [Python Packaging Authority]: https://github.com/pypa/
-[PSF Code of Conduct]: https://www.python.org/psf/conduct/
+[PSF Code of Conduct]: https://policies.python.org/python.org/code-of-conduct/