Support for PHP 8.0, PHP 8.1 and PHP 8.2
I am currently investing some time into Ratchet and want to test the project against PHP 8.0+. Inspired by https://github.com/ratchetphp/Ratchet/pull/923 by @WyriHaximus, I wanted to try it out myself. Before running the test suite with the PHP 8 versions, I first have to update PHPUnit to the latest version (at least v8, maybe v9 as a first step) and make it work across the current supported PHP versions for this project (PHP 5.4 - PHP 7.4). I did the same thing for ReactPHP a while ago (e.g. https://github.com/reactphp/http/pull/364), so I already know my ways around.

Will keep you posted :+1: 