余额查询

**请求示例**  

https://query.deerapi.com/user/quota/?key=sk-xxx


## 返回体示例
```json
{
  "username": "example_user",
  "total_quota": 2105.234088,
  "total_used_quota": 21.065912,
  "request_count": 1221,
  "keys": [
    {
      "name": "tts测试",
      "remain_quota": 8.93872,
      "used_quota": 2.099206
    },
    {
      "name": "并发测试",
      "remain_quota": 10,
      "used_quota": 0
    },
    {
      "name": "mj测试",
      "remain_quota": 8.55,
      "used_quota": 1.45
    },
    {
      "name": "测试key",
      "remain_quota": 999999999,
      "used_quota": -1
    }
  ]
}