Add php8.1 enum support

[tdumalin]

Hi,

I've created an issue on StateMachineBundle (#70) but i realized that it's on this repo that we have to work.
So this is an implementation for php8.1 enum support, let me know what do you think.

[lchrusciel]

Hey @tdumalin,

thanks a lot for your contribution! I would need to sit into how to properly solve it here. Also, such code would require to be available only with PHP8.1 enabled

[tdumalin]

@lchrusciel

Yes indeed, I've seen the build errors and parseError could not be avoided in php < 8.1. The only solution would be to add php version in composer.json but it will be very tricky to manage.
Let me know if you've found a solution 👍

[coldic3]

Hey! What do you guys think about skipping these tests for PHP <8.1? Skipping examples can be used for that:

if (version_compare(PHP_VERSION, '8.1.0', '<')) {
    throw new \PhpSpec\Exception\Example\SkippingException('Requires at least PHP 8.1.');
}

[tdumalin]

@coldic3 ,
I just pushed something quite similar with version compare,
wait and see if the build will pass

[coldic3]

Hey @tdumalin, I see tests passed 🙂

I've added some small comments. I also wonder if the states key in the configuration might not be required while using enum 🤔