test with php 8

[dbu]

• need to allow doctrine/dbal 3
• replace dbunit with our own fixtures handling: Wanted (Maybe?): New Maintainer sebastianbergmann/dbunit#217

[dbu]

via @YetiCGN

PHP Fatal error:  Declaration of Jackalope\Test\Fixture\XMLDocument::save($file = null) must be compatible with DOMDocument::save(string $filename, int $options = 0) in vendor/jackalope/jackalope-doctrine-dbal/tests/Jackalope/Test/Fixture/XMLDocument.php on line 123
Errors parsing vendor/jackalope/jackalope-doctrine-dbal/tests/Jackalope/Test/Fixture/XMLDocument.php