GHSA-8CWQ-4CMF-PX73 PocketMine-MP invalid skin geometry JSON data leading to server crash

Impact pocketmine\entity\Skin doesn't correctly handle errors produced by adhocore/json-comment, which throws RuntimeException rather than returning false as PocketMine-MP expects. This leads to a server crash if the skin geometry data is invalid for some reason e.g. a syntax error. Patches...