run-tests: update minimum required PHP version.

[marcosmarcolin]

The use of Union Types in https://github.com/php/php-src/blob/master/run-tests.php#L3161 is only supported in PHP >= 8.0.0

I believe the information should be updated, or Union Types should be removed.

[cmb69]

Thank you!

Since this has been introduced via 948b2bc, I think we should apply to PHP-8.4 (no need to change the base branch of the PR, though).

[jorgsowa]

Thank you for this PR. I didn't think about bumping the minimum PHP version for the script.

[cmb69]

We may consider to employ some tooling which verifies that we don't use features we do not want to use at some point.

[marcosmarcolin]

Hello @cmb69 @jorgsowa,

I don't see any problem in sending it to the 8.4 branch.

However, IMO, if it were to go to the main branch, I don't see it as a problem either, since if someone tries to run the tests with PHP < 8.0 they will get a fatal error.

About compatibility, it makes sense to use something to detect this early, like PHPCompatibility (then we would have to discuss the use of third-party tools, etc.).

[cmb69]

However, IMO, if it were to go to the main branch, I don't see it as a problem either, since if someone tries to run the tests with PHP < 8.0 they will get a fatal error.

Right, but this comment is not a guard anyway, but rather some documentation. Thus I've applied to PHP-8.4 and merged up.

About compatibility, it makes sense to use something to detect this early, like PHPCompatibility (then we would have to discuss the use of third-party tools, etc.).

Indeed, some discussion would be needed, but at least we have now a policy on using third-party code, so that might not be a problem.