Update go dependencies

vendor/golang.org/x/crypto/ssh/messages.go

@@ -23,6 +23,10 @@ const (
 	msgUnimplemented = 3
 	msgDebug         = 4
 	msgNewKeys       = 21
+
+	// Standard authentication messages
+	msgUserAuthSuccess = 52
+	msgUserAuthBanner  = 53
 )
 
 // SSH messages:
@@ -133,16 +137,6 @@ type userAuthFailureMsg struct {
 	PartialSuccess bool
 }
 
-// See RFC 4252, section 5.1
-const msgUserAuthSuccess = 52
-
-// See RFC 4252, section 5.4
-const msgUserAuthBanner = 53
-
-type userAuthBannerMsg struct {
-	Message string `sshtype:"53"`
-}
-
 // See RFC 4256, section 3.2
 const msgUserAuthInfoRequest = 60
 const msgUserAuthInfoResponse = 61