ci: update ws build step

Author: Apolo151

.github/workflows/ros2_launch_tests.yaml

@@ -80,8 +80,8 @@ jobs:
             - name: Run launch tests
               run: |
                   source /opt/ros/humble/setup.bash
-                  source /usr/share/gazebo/setup.sh
                   source install/setup.bash
+                  source /usr/share/gazebo/setup.bash
                   colcon test --packages-select custom_robots --event-handlers console_direct+ --return-code-on-test-failure
 
             - name: Show test results