OPcache generates a warning with PHP >= 8.5

[Frzk]

The Zend OPcache extension is included into PHP, starting with PHP 8.5. (see https://www.php.net/manual/fr/intro.opcache.php)

The buildpack always adds a config directive that instructs PHP to load the extension from an external .so file, which is useless with PHP >= 8.5.
This generates an unpleasant (but non-blocking) warning.