misc: 메시지 삭제 API 정리

hwe/sammo/API/Message/DeleteMessage.php

@@ -4,12 +4,9 @@ namespace sammo\API\Message;
 
 use sammo\Session;
 use DateTimeInterface;
-use sammo\DB;
 use sammo\Message;
 use sammo\Validator;
 
-use function sammo\getMailboxList;
-
 class DeleteMessage extends \sammo\BaseAPI
 {
   public function validateArgs(): ?string