gazebo: bump dep

Author: voshch

_meta/repos/gazebo.repos

@@ -2,7 +2,7 @@ repositories:
   gazebo/arena_gz_plugins:
     type: git
     url: https://github.com/voshch/arena_gz_plugins.git
-    version: jazzy
+    version: harmonic
   # gazebo/ros_gz:
   #   type: git
   #   url: https://github.com/voshch/ros_gz.git