Fix dependency injection deprecation

[thomas-hiron]

This fixes the following deprecation:

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 "Ibericode\Vat\Bundle\DependencyInjection\VatExtension".