Remove map_msgs exported dependency (#524)

* This is unused

Signed-off-by: Ryan Friedman <25047695+Ryanf55@users.noreply.github.com>

Author: Ryanf55

grid_map_rviz_plugin/CMakeLists.txt

@@ -136,7 +136,6 @@ ament_export_dependencies(
   Qt5
   rviz_common
   geometry_msgs
-  map_msgs
   nav_msgs
   rclcpp
 )