deps: update dependency phpunit/phpunit to v13

Author: renovate-bot

samples/snippets/php-snippets/composer.json

@@ -6,7 +6,7 @@
     "symfony/http-client": "^7.2"
   },
   "require-dev": {
-    "phpunit/phpunit": "^12.0"
+    "phpunit/phpunit": "^13.0"
   },
   "config": {
     "allow-plugins": {