Replaced instances of Gazebo Garden with Gazebo Harmonic (#238) (#265)

(cherry picked from commit 4247e6f)

Co-authored-by: Evan Palmer <evanp922@gmail.com>

Author: mergify[bot]

docs/docs/tutorials/control.mdx

@@ -16,7 +16,7 @@ tutorial.
 
 The following ROS 2 dependencies are required for this tutorial:
 
-* Gazebo Garden or newer
+* Gazebo Harmonic or newer
 * [ardusub_driver](https://github.com/Robotic-Decision-Making-Lab/ardusub_driver)
   (for use with the BlueROV2 vehicle models)
 * [auv_controllers](https://github.com/Robotic-Decision-Making-Lab/auv_controllers)

docs/docs/tutorials/simulation.mdx

@@ -18,7 +18,7 @@ project's needs.
 
 This tutorial has the following dependencies:
 
-* Gazebo Garden or newer
+* Gazebo Harmonic or newer
 * [ardusub_driver](https://github.com/Robotic-Decision-Making-Lab/ardusub_driver)
   (for use with the BlueROV2 vehicle models)
 

docs/docs/tutorials/teleop.mdx

@@ -17,7 +17,7 @@ keyboard.
 
 The following ROS 2 dependencies are required for this tutorial:
 
-* Gazebo Garden or newer
+* Gazebo Harmonic or newer
 * [ardusub_driver](https://github.com/Robotic-Decision-Making-Lab/ardusub_driver)
 * [auv_controllers](https://github.com/Robotic-Decision-Making-Lab/auv_controllers)
 * [teleop_twist_keyboard](https://github.com/ros2/teleop_twist_keyboard)
@@ -68,7 +68,7 @@ This tutorial describes how to teleoperate a simulated BlueROV2 using a gamepad.
 
 The following ROS 2 dependencies are needed for this tutorial:
 
-* Gazebo Garden or newer
+* Gazebo Harmonic or newer
 * [ardusub_driver](https://github.com/Robotic-Decision-Making-Lab/ardusub_driver)
 * [auv_controllers](https://github.com/Robotic-Decision-Making-Lab/auv_controllers)
 * [mobile_to_maritime](https://github.com/Robotic-Decision-Making-Lab/mobile_to_maritime)