Include mutex header for usage of scoped_lock (#3532)

Since std::scoped_lock is used in the implementations, the header
defining this should be included.

Author: fmauch

moveit_ros/visualization/planning_scene_rviz_plugin/src/background_processing.cpp

@@ -34,6 +34,8 @@
 
 /* Author: Ioan Sucan */
 
+#include <mutex>
+
 #include <moveit/planning_scene_rviz_plugin/background_processing.hpp>
 #include <rclcpp/logger.hpp>
 #include <rclcpp/logging.hpp>