Allow even lowe phpunit

Author: frankdejonge

composer.json

@@ -34,6 +34,6 @@
         "test": "phpunit src"
     },
     "require-dev": {
-        "phpunit/phpunit": "^10.0 || ^11.5"
+        "phpunit/phpunit": "^9.0 || ^10.0 || ^11.5"
     }
 }