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

@@ -18,7 +18,7 @@
     "require-dev": {
         "phpstan/phpstan": "^2.1.29",
         "phpstan/phpstan-phpunit": "^2.0.7",
-        "phpunit/phpunit": "^12.3.14"
+        "phpunit/phpunit": "^12.3.15"
     },
     "autoload": {
         "psr-4": {