Add buildtool_export_depend on ament_cmake_ros_core (#558)

Signed-off-by: Shane Loretz <sloretz@intrinsic.ai>

Author: sloretz

package.xml

@@ -15,6 +15,7 @@
 
   <buildtool_depend>ament_cmake</buildtool_depend>
   <buildtool_depend>ament_cmake_ros_core</buildtool_depend>
+  <buildtool_export_depend>ament_cmake_ros_core</buildtool_export_depend>
 
   <depend>libatomic</depend>