Update announcements.json

announcements.json

 [
-    {"id":27,"title":"更新维护，暂停止服务，见谅","url":"https://my-card.in/","created_at":"2014-12-09T12:30:06+08:00","updated_at":"2014-12-29T12:30:06+08:00"},
     {"id":23,"title":"竞赛联盟～暑假赛","url":"http://www.duelcn.com/forum.php?mod=viewthread&tid=60802&extra=","created_at":"2014-08-01T19:34:06+08:00","updated_at":"2014-08-11T19:34:06+08:00"},
     {"id":21,"title":"捐款地址更改为 my-card.in/donate ","url":"http://my-card.in/donate","created_at":"2014-05-06T10:34:06+08:00","updated_at":"2014-05-06T10:34:06+08:00"},
     {"id":18,"title":"游戏王竞赛联盟~周赛","url":"http://www.duelcn.com/thread-59882-1-1.html","created_at":"2013-12-01T18:55:06+08:00","updated_at":"2030-10-22T10:34:06+08:00"},