changelog update

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
-v 7.13.0 (unreleased)
+v 7.13.0
   - Only enable HSTS header for HTTPS and port 443 (Stan Hu)
   - Fix user autocomplete for unauthenticated users accessing public projects (Stan Hu)
   - Fix redirection to home page URL for unauthorized users (Daniel Gerhardt)