Fix stray comma in CORS

Author: facchinm

main.go

@@ -199,7 +199,7 @@ func main() {
 
 			socketHandler := wsHandler().ServeHTTP
 
-			extraOriginStr := "https://create.arduino.cc, http://create.arduino.cc, https://create-dev.arduino.cc, http://create-dev.arduino.cc, https://create-intel.arduino.cc, http://create-intel.arduino.cc,"
+			extraOriginStr := "https://create.arduino.cc, http://create.arduino.cc, https://create-dev.arduino.cc, http://create-dev.arduino.cc, https://create-intel.arduino.cc, http://create-intel.arduino.cc"
 
 			for i := 8990; i < 9001; i++ {
 				extraOriginStr = extraOriginStr + ", http://localhost:" + strconv.Itoa(i) + ", https://localhost:" + strconv.Itoa(i)