Update index.ixx

Author: masx200

traffic-light-controlled-intersection/index.ixx

@@ -1,8 +1,9 @@
 module;
 #include <functional>
 #include <mutex>
-using namespace std;
+
 export module leetcode_test.traffic_light_controlled_intersection.TrafficLight;
+using namespace std;
 namespace leetcode_test ::traffic_light_controlled_intersection {
 
 export class TrafficLight {
@@ -30,4 +31,4 @@ public:
         crossCar();
     }
 };
-} // namespace leetcode_test::traffic_light_controlled_intersection
+} // namespace leetcode_test::traffic_light_controlled_intersection