Cache also .venv for mujoco_ros2_control

[christophfroehlich]

Could improve ros-controls/mujoco_ros2_control#193
But: it needs to succeed once on the default branch to have a successful cache store, which then can be restored the next time:

ros2_control_ci/.github/workflows/reusable-industrial-ci-with-cache.yml

Lines 110 to 117 in 36196e4

	- name: Restore ccache folder
	uses: actions/cache/restore@v5
	with:
	path: ${{ env.CCACHE_DIR }}
	key: ccache-${{ env.CACHE_PREFIX }}-${{ github.sha }}-${{ github.run_id }}
	restore-keys: |
	ccache-${{ env.CACHE_PREFIX }}-${{ github.sha }}
	ccache-${{ env.CACHE_PREFIX }}

👀 @saikishor maybe we have to increase the timeout to let it be installed for the first time in every installation, it even fails in my local devcontainer:

3/6 Test #3: test_robot_launch_mjcf_generation_test.py ..........................***Timeout  75.36 sec