Mixed is reserved in php8

[brunobg]

Run composer run-script test
> ./vendor/bin/phpunit --configuration phpunit.xml tests/
PHPUnit 8.5.14 by Sebastian Bergmann and contributors.

PHP Fatal error:  Cannot use 'Mixed' as class name as it is reserved in /home/runner/work/modelarium/modelarium/Modelarium/Types/Mixed.php on line 13
Script ./vendor/bin/phpunit --configuration phpunit.xml tests/ handling the test event returned with error code 255
Error: Process completed with exit code 255.