Fix the PHP version check with the use of Semver

[tvbeek]

The current check only takes the PHP version from the composer.json file and checks if the current version is the same or higher. But composer has more options, that if used can be conflicted or incorrect tested. See: https://getcomposer.org/doc/articles/versions.md#summary

I have changed the behaviour by using the Semver package from composer to check it.

The only question I have is the change on the getRequiredPhpVersion function. Because it is a public function I didn't want to change it and added a new function getRequiredPhpConstraint. That means that there is now a function that isn't used by the check. If wanted I can mark it as deprecated

[Namoshek]

In my opinion, the code can be removed because your suggested changes are already breaking the backwards-compatibility, so why bother about one function? A compromise could be though to keep the old check logic as well and make the check configurable. I.e. introduce something like 'semver_comparison' => true as configuration for the check. But personally, I would say the semver comparison is the better one and should be used in future.

Just a quick thought right now: We are only checking the php-cli version currently. Is there any way we could also check the php-fpm version (if php-fpm is used)?

[mpociot]

Thanks for the PR. I also think that the semver check is better and that we can remove the old method.
Can you adjust the PR?

[tvbeek]

Thanks for the feedback, I have remove the old function (And the test for that function)