Update dependency slam/php-cs-fixer-extensions to ^3.15.0

| datasource | package                      | from   | to     |
| ---------- | ---------------------------- | ------ | ------ |
| packagist  | slam/php-cs-fixer-extensions | 3.14.0 | 3.15.0 |

Author: renovate[bot]

composer.json

@@ -15,7 +15,7 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^12.5.14",
-        "slam/php-cs-fixer-extensions": "^3.14.0"
+        "slam/php-cs-fixer-extensions": "^3.15.0"
     },
     "autoload": {
         "files": [