feat: support get group notice #493

[qianjunakasumi]

检查清单

• 合并 feat: support get group announcement MiraiGo#258
• 更新 go.mod

响应示例

{
  "data": [
    {
      "sender_id": 114514,
      "publish_time": 1919810,
      "message": {
        "text": "我永远喜欢樱花千代",
        "images": [
          {
            "height": "342",
            "width": "314",
            "id": "SOREzKY8sB3N6vvVos6WwiaWgsEicCnrGuH1ZmhC3P8QA"
          }
        ]
      }
    },
    {
      "sender_id": 114514,
      "publish_time": 1919810,
      "message": {
        "text": "test",
        "images": []
      }
    }
  ],
  "retcode": 0,
  "status": "ok"
}

关联 Issue

close #493