vendor: Update pfilter and go-stun (fixes #4561)

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4575

vendor/github.com/ccding/go-stun/stun/const.go

@@ -41,20 +41,24 @@ const (
 	NATRestricted
 	NATPortRestricted
 	NATSymmetricUDPFirewall
+
+	// Deprecated spellings of these constants
+	NATSymetric            = NATSymmetric
+	NATSymetricUDPFirewall = NATSymmetricUDPFirewall
 )
 
 var natStr map[NATType]string
 
 func init() {
 	natStr = map[NATType]string{
-		NATError:               "Test failed",
-		NATUnknown:             "Unexpected response from the STUN server",
-		NATBlocked:             "UDP is blocked",
-		NATFull:                "Full cone NAT",
+		NATError:                "Test failed",
+		NATUnknown:              "Unexpected response from the STUN server",
+		NATBlocked:              "UDP is blocked",
+		NATFull:                 "Full cone NAT",
 		NATSymmetric:            "Symmetric NAT",
-		NATRestricted:          "Restricted NAT",
-		NATPortRestricted:      "Port restricted NAT",
-		NATNone:                "Not behind a NAT",
+		NATRestricted:           "Restricted NAT",
+		NATPortRestricted:       "Port restricted NAT",
+		NATNone:                 "Not behind a NAT",
 		NATSymmetricUDPFirewall: "Symmetric UDP firewall",
 	}
 }