[ticket/12547] Rename jquery.js to jquery.min.js in assets directory

phpBB uses the minified version of jQuery hence the rename.

PHPBB3-12547
Merge remote-tracking branch 'n-aleha/ticket/12547' into develop-ascraeus

* n-aleha/ticket/12547:
  [ticket/12547] Rename jquery.js to jquery.min.js in assets directory