PHP 8.1: strftime and gmstrftime functions are deprecated

[kaetemi]

https://php.watch/versions/8.1/strftime-gmstrftime-deprecated

[kaetemi]

Deprecated: Function strftime() is deprecated in Y:\ryzomcore4\code\web\public_php\admin\smarty\Smarty_Compiler.class.php on line 395

[kaetemi]

Find all uses of these functions in the codebase, and update them.