Increase CI matrix to test against more recent PHPUnit & PHP versions

[Jean85]

This is a followup to #348, and tries to add more configuration to test.
Let me know if you want me to follow some specific approach, for now I'm trying a balance between testing all the versions and not having too many jobs to execute.

@Jan0707 WDYT about dropping the custom actions for Composer and migrati to ramsey/composer-install? It has all in one, caching included.

[Jean85]

SA failure is due to the fact that we're using nikic/php-parser v4, while PHPStan 2 uses v5 internally.

$ composer why-not nikic/php-parser 5
phpunit/php-code-coverage 9.0.0 requires nikic/php-parser (^4.7) 
sebastian/complexity      2.0.0 requires nikic/php-parser (^4.7) 
sebastian/lines-of-code   1.0.0 requires nikic/php-parser (^4.6) 

The same failure does not happen in the CI job with PHPUnit 9.6.0, since it allows v5 since php-code-coverage v9.2.30

I fixed it by running composer update phpunit/php-code-coverage nikic/php-parser -w --minimal-changes, the new --minimal-changes option is great! 😄

[Jean85]

@Jan0707 WDYT about dropping the custom actions for Composer and migrati to ramsey/composer-install? It has all in one, caching included.

@Jan0707 I did this in the last commit, let me know if it's ok or if I should drop it.

[Jean85]

Sorry, I needed to ping you @alexander-schranz 😓

[alexander-schranz]

Fine with the using ramsey github action.