Update dependency phpunit/phpunit to v12

Author: renovate[bot]

composer.json

@@ -39,7 +39,7 @@
         "php-di/php-di": "^6.4 || ^7.0",
         "php-http/psr7-integration-tests": "^1.4",
         "phpstan/phpstan": "^2.1",
-        "phpunit/phpunit": "^9.6",
+        "phpunit/phpunit": "^12.0",
         "sunrise/coding-standard": "^1.0",
         "vimeo/psalm": "^5.26 || ^6.0"
     },