PHP 8 Support and Modern Testing

I've done a small overhaul to bring us up to date for PHP 8 and PHP 8.1. The minimum PHP version for this library is now PHP 8.

• Updated PHPUnit Tests to latest version
• Added PHPStan tests - Now Level 9 compliant! 🎉
• Added automated mutation testing

array_map Refactor

The main point of this release is the refactor in Socket to utilize array_map instead of multiple foreach() calls.

This release also addresses some code formatting and other maintenance items (allowed failures, copyright year, generic code smells)

First "Release"

I'm going to start tagging "releases" with SemVer now (I apparently forgot to do it in the past).

This release marks the following:

• First Release, woo! But not stable.. boo!
• Moved from PSR-0 to PSR-4
• Moved tests out of src/
• Added timeout feature courtesy of @viniciusjarina