Adapt magic methods for PHP 8.5 (#18)

chore: add support for latest PHPUnit versions and update CI workflows

* Support PHPUnit 10
* Support PHPUnit 11
* Bump actions and improve workflow

chore: update .gitattributes

* Update .gitattributes after TravisCI -> GH
* Remove test folder and phpunit config from vendor bundles

I previously needed it, but on Debian I can use the git mode and strip this gitattributes file

ci: set up git to use LF

Merge pull request #6 from ausi/fix/php-8-compat

Fix PHP 8.0 warning

Merge pull request #4 from code-lts/master

Some maintainance

Merge pull request #3 from carusogabriel/fix/magic-methods-signature

Fix magic method `__sleep` return value

Add coverage for mixed value type