Test against php 8.1 in not experimental mode

[sergiy-petrov]

No description provided.

[coveralls]

Coverage remained the same at 100.0% when pulling ffe6fd5 on sergiy-petrov:sergiy-petrov-patch-1 into a8e4ce9 on slimphp:4.x.

[t0mmy742]

CI already passed successfully with PHP 8.1. It will not break anything.
PHP 8.1 is not official yet. It should be officially released Nov 25 2021 (but RC5 already released, so nothing should change but bugfix).
@l0gicgate do you think we should do analyses (PHPCS & PHPStan & coverage) on PHP 8.1 too ? Or maybe we should wait for official release.

[sergiy-petrov]

@t0mmy742 I've added option to run phpstan on php 8.1 in separate branch (it's on my fork). Seems it has a lot of errors however job is passed. Not sure why does it behave like that. You could see it on my fork:

https://github.com/sergiy-petrov/Slim/runs/4046667668?check_suite_focus=true

[t0mmy742]

It seems like phpstan is not ready for PHP 8.1 yet.
We should not do analyses on this version of PHP (I'm answering myself, I know x) )

[l0gicgate]

It looks like PHPStan 1.0.0 was just released. Is that what we're waiting for? 🤔