Add PHP 8.3 and Laravel 11 compatibility

[BernhardK91]

What I did

• Migrate PHPUnit configuration
• Updated packages to PHP 8.3
• Updated packages for Laravel 11 compatibility
• Fixed PHPStan errors
• Migrated nunomaduro/larastan to larastan/larastan

How to test

• use PHP 8.3
• run composer install
• run vendor/bin/phpstan
• run vendor/bin/phpunit

Does this need an update to the documentation?

I am not sure abot that.

Fixes #302, #304

[erickcg]

Hope this gets merged soon