global 接口，返回日期

[zhangmuqing]

按此格式返回：

{
  "code": "90000",
  "message": "success",
  "data": {
    "global": {
      // 在此处新增 last_update_date 字段
      "last_update_date ": "2020-04-09",
      "confirmed_add": 1475773,
      "deaths_add": 86626,
      "recovered_add": 323390,
      "country": {
        "Afghanistan": {
          "confirmed_add": 443,
          "deaths_add": 14,
          "recovered_add": 29
        }
      }
    }
  }
}