Update dependency phpunit/phpunit to ^12.3.15 (#1031)

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

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

composer.json

@@ -43,7 +43,7 @@
         "phpunit/php-code-coverage": "^12.4.0",
         "phpunit/php-file-iterator": "^6",
         "phpunit/php-timer": "^8",
-        "phpunit/phpunit": "^12.3.14",
+        "phpunit/phpunit": "^12.3.15",
         "sebastian/environment": "^8.0.3",
         "symfony/console": "^6.4.20 || ^7.3.2",
         "symfony/process": "^6.4.20 || ^7.3.0"