PHP 8.1: silence the deprecation notice about jsonSerialize() return type

Author: MarkBaker

src/Enum.php

@@ -311,7 +311,7 @@ public static function __callStatic($name, $arguments)
      * @link http://php.net/manual/en/jsonserializable.jsonserialize.php
      * @psalm-pure
      */
-    #[ReturnTypeWillChange]
+    #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
         return $this->getValue();