CI pipeline issue: PHPUnit TestSuite.php generates PHP fatal error

[Angatar]

It seems there is currently an issue with the PHPUnit version used in the CI pipeline:

PHP Fatal error: Declaration of PHPUnit\Framework\TestSuite::run(): void must be compatible with PHPUnit\Framework\Test::run(?PHPUnit\Framework\TestResult $result = null): PHPUnit\Framework\TestResult in /home/runner/work/schema-generator/schema-generator/vendor/phpunit/phpunit/src/Framework/TestSuite.php on line 318

Can you fix it?

Details:
https://github.com/api-platform/schema-generator/actions/runs/7142451910/job/19451775510?pr=415

Originally posted by @Angatar in #415 (comment)

BTW: I got no error on the local runs of the PHPunit tests with PHP 7.4, 8.0, 8.1, 8.2 and 8.3

[Angatar]

@dunglas #420 fixed it, thanks!

PR #421 now pass CI :)