Fix directory structure for traffic lights

traffic_lights/src/lib.cpp

@@ -2,7 +2,8 @@
 // Created by Gabriel Augendre on 27/04/2021.
 //
 
-#include "lib.h"
+#include <lib.h>
+#include <Arduino.h>
 
 void waitForButton() {
     while (digitalRead(BUTTON) == HIGH) {}

traffic_lights/src/main.cpp

@@ -1,5 +1,5 @@
 #include <Arduino.h>
-#include "lib.h"
+#include <lib.h>
 
 void setup() {
     pinMode(GREEN, OUTPUT);