Deprecation notice on Symfony's DependencyInjection/Extension

[ReSpawN]

The "Symfony\Component\HttpKernel\DependencyInjection\Extension" class is considered internal since Symfony 7.1, to be deprecated in 8.1; use Symfony\Component\DependencyInjection\Extension\Extension instead. It may change without further notice. You should not use it from "FOS\JsRoutingBundle\DependencyInjection\FOSJsRoutingExtension".

Changing the extension base class would only cause the drop of getXsdValidationBasePath and getNamespace, which are easily overwritten (see \Symfony\Component\DependencyInjection\Extension\Extension).