我添加方法如下，但是请求一直报这个错误，确认了证书是没问题的。

CA_ERROR 证书出错，请登录微信支付商户平台下载证书

代码如下：

transport := &http.Transport{
        DialContext: (&net.Dialer{
            Timeout:   500 * time.MillSecond,
            KeepAlive: 30 * time.Second,
            DualStack: true,
        }).DialContext,
        MaxIdleConns:        gConf.HTTP.MaxIdelConns,
        IdleConnTimeout:     3 * time.Minute,
        TLSHandshakeTimeout: 3 * time.Second,
        MaxIdleConnsPerHost: gConf.HTTP.MaxIdelConns,
    }

        certP12, err := ioutil.ReadFile("apiclient_cert.p12")
        if err != nil {
            panic(err)
        }


        blocks, err := pkcs12.ToPEM(certP12, "100000001")
        if err != nil {
            panic(err)
        }


        var pemData []byte
        for _, b := range blocks {
            pemData = append(pemData, pem.EncodeToMemory(b)...)
        }


        cert, err := tls.X509KeyPair(pemData, pemData)
        if err != nil {
            panic(err)
        }


        transport.TLSClientConfig = &tls.Config{
            Certificates: []tls.Certificate{cert},
        }
  
    httpClient := &http.Client{Transport: transport}
}