/// <summary>
/// 上传客服头像
/// </summary>
/// <param name="access_token">公众号access token</param>
/// <param name="kf_account">完整客服帐号，格式为：帐号前缀@公众号微信号</param>
/// <param name="filepath">头像物理路径</param>
/// <param name="timeout">超时时间</param>
/// <returns></returns>
public JsonResult UploadKFHeaderImg(string access_token, string kf_account, string filepath, int timeout = 1200000)
{
string url = $"{Config.WxApi}customservice/kfaccount/uploadheadimg?access_token={access_token}&kf_account={kf_account}";
Dictionary <string, string> dic = new Dictionary <string, string>();
dic.Add("media", filepath);
MaterialService service = new MaterialService();
JsonResult result = service.AddFileToWeChat <JsonResult>(url, dic, timeout);
return(result);
}