AddRemoteProvider,reading config from etcd3

[joinzhao]

配置连接至etcd3， 读取相关键值对， 连接正常， 但是读取配置时，读取不到数据

当前 etcd version

etcd Version: 3.5.8  
Git SHA: 217d183e5  
Go Version: go1.19.8  
Go OS/Arch: linux/amd64

demo

	if err != nil {
		return err
	}
	viper.SetConfigFile("json")

	err = viper.ReadRemoteConfig()
	if err != nil {
		return err
	}
	fmt.Println("-> ", viper.AllSettings())
	return viper.Unmarshal(dest)

result

->  map[]
&{<nil> }

now config

{
    "app": {
        "serve": "123"
    },
    "tag":"string"
}