Update dependency phpunit/phpunit to ^12.3.15

| datasource | package         | from    | to      |
| ---------- | --------------- | ------- | ------- |
| packagist  | phpunit/phpunit | 12.3.14 | 12.3.15 |

Author: renovate[bot]

composer.json

@@ -17,7 +17,7 @@
         "phpstan/phpstan": "^2.1.29",
         "phpstan/phpstan-phpunit": "^2.0.7",
         "phpstan/phpstan-strict-rules": "^2.0.7",
-        "phpunit/phpunit": "^12.3.14",
+        "phpunit/phpunit": "^12.3.15",
         "slam/php-cs-fixer-extensions": "^3.13.0",
         "symfony/console": "^7.3.4"
     },