Update dependency phpunit/phpunit to v12

Author: renovate[bot]

composer.json

@@ -14,7 +14,7 @@
         "php-parallel-lint/php-parallel-lint": "^1.2",
         "phpstan/phpstan-phpunit": "^2.0",
         "phpstan/phpstan-strict-rules": "^2.0",
-        "phpunit/phpunit": "^9.6"
+        "phpunit/phpunit": "^12.0"
     },
     "config": {
         "platform": {