我测试的时候回调的时候提示下面这个错误请问是什么原因呢

RequestException in CurlFactory.php line 187:
cURL error 60: SSL certificate problem: unable to get local issuer certificate (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)

回调地址是

GitHub_REDIRECT_URI=http://127.0.0.1:8000/login/callback/