composer安装

报错 GuzzleHttp\HandlerStack' not found

官方示例

use GuzzleHttp\Exception\RequestException;
use WechatPay\GuzzleMiddleware\WechatPayMiddleware;
use WechatPay\GuzzleMiddleware\Util\PemUtil;
use GuzzleHttp\HandlerStack;

y运行的时候
$stack = GuzzleHttp\HandlerStack::create(); 这段代码报错 也查抄不到GuzzleHttp ，是否需要自己在安装这个包