tests: fix php 8.1

Author: Gemorroj

composer.json

@@ -15,7 +15,7 @@
         }
     ],
     "require-dev": {
-        "phpunit/phpunit": "^9.5",
+        "phpunit/phpunit": "^9.5.16",
         "friendsofphp/php-cs-fixer": "^3.0"
     },
     "autoload": {