nav2_waypoint_follower: Fix opencv includes (#4287)

Signed-off-by: Silvio Traversaro <silvio@traversaro.it>

Author: traversaro

nav2_waypoint_follower/include/nav2_waypoint_follower/plugins/photo_at_waypoint.hpp

@@ -32,8 +32,8 @@
 
 #include "sensor_msgs/msg/image.hpp"
 #include "nav2_core/waypoint_task_executor.hpp"
-#include "opencv4/opencv2/core.hpp"
-#include "opencv4/opencv2/opencv.hpp"
+#include "opencv2/core.hpp"
+#include "opencv2/opencv.hpp"
 #include "cv_bridge/cv_bridge.hpp"
 #include "image_transport/image_transport.hpp"