fix: ci failure on testbench 9.x-dev

[KentarouTakeda]

Hi! Are you eating vegetables?

1. Laravel11 requires orchestra/testbench@9.x-dev. The version of symfony/process that this version depends on is fixed to 7 .
   orchestral/testbench@c2bbe49
2. friendsofphp/php-cs-fixer requires symfony/process@6, so it cannot coexist with orchestra/testbench@9.x-dev, which requires 7.
   https://github.com/PHP-CS-Fixer/PHP-CS-Fixer/blob/v3.37.1/composer.json#L37
3. But composer.json explicitly requires Laravel 11
   https://github.com/mpyw/laravel-database-advisory-lock/blob/v4.3.0/.github/workflows/ci.yml#L82

Fixed that dependency resolution could not be performed due to the above conflict.

Since PHPStan is not running in Laravel 11, php-cs-fixer is also considered to be of low importance and is skipped.

Best WIP.

[KentarouTakeda]

FYI: The CI run results on my branch are as follows:
https://github.com/KentarouTakeda/mpyw-laravel-database-advisory-lock/actions/runs/6722350225/job/18270106302