change socks5 client to provide userpass auth method only if auth configured

connector/socks/v5/connector.go

@@ -46,12 +46,14 @@ func (c *socks5Connector) Init(md md.Metadata) (err error) {
 	selector := &clientSelector{
 		methods: []uint8{
 			gosocks5.MethodNoAuth,
-			gosocks5.MethodUserPass,
 		},
 		User:      c.options.Auth,
 		TLSConfig: c.options.TLSConfig,
 		logger:    c.options.Logger,
 	}
+	if selector.User != nil {
+		selector.methods = append(selector.methods, gosocks5.MethodUserPass)
+	}
 	if !c.md.noTLS {
 		selector.methods = append(selector.methods, socks.MethodTLS)
 		if selector.TLSConfig == nil {