Support Symfony 6.0

[filkaris]

Hello!

This change is required for the package to be installed in a Symfony 6.0 installation.

I manually tried the cuzzle package with the new Symfony 6.0 demo, and it works just fine

Symfony changelog shows no changes in version 6.0 for the process component https://github.com/symfony/process/blob/5.4/CHANGELOG.md

When trying to use this package in a symfony installation, the symfony/process dependency does not allow it to be installed because of this json block inside composer.json, forcing all symfony/* packages to be at least version 6

    "extra": {
        "symfony": {
            "allow-contrib": true,
            "require": "6.0.*"
        }
    }

[hopeseekr]

PleaSE... I really need this...