Add PHP 8.4 support

[joanhey]

The tests pass, but show deprecations with the symfony/string v5.4.0 class in PHP 8.4 lowest test.

Symfony/string is fixed symfony/string@bce7504

PD: perhaps it'll be better to change in composer.json :

"require": {
        "php": "~8.2.0 || ~8.3.0 || ~8.4.0",

with

"require": {
        "php": ">=8.2",

Changed to "php": ">=8.2"

Fix #871
that break PestPHP pestphp/pest#1199

[Slamdunk]

I don't like the CI build on 8.4 to be successful: https://github.com/paratestphp/paratest/actions/runs/10473712966/job/29006479710?pr=872#step:3:19

pcov is not yet compatible with 8.4, krakjoe/pcov#111

[Slamdunk]

Apparently there's an infinite loop somewhere with PHP 8.4, but I can't debug it yet locally because the pcov PECL extension hasn't been updated yet, we need to wait