fix metadata

dialer/ftcp/metadata.go

@@ -1,22 +1,10 @@
 package ftcp
 
 import (
-	"time"
-
 	md "github.com/go-gost/core/metadata"
 )
 
-const (
-	dialTimeout = "dialTimeout"
-)
-
-const (
-	defaultDialTimeout = 5 * time.Second
-)
-
-type metadata struct {
-	dialTimeout time.Duration
-}
+type metadata struct{}
 
 func (d *ftcpDialer) parseMetadata(md md.Metadata) (err error) {
 	return