github actions catkin build example?

edit

I've got something working here: https://github.com/lucasw/frei0r_imag... (see also https://github.com/lucasw/frei0r_imag... for how the results are reported)

name: Noetic Ubuntu 20.04

on:
  push:
  pull_request:
  workflow_dispatch:

jobs:
  build:
    runs-on: ubuntu-20.04
    env:
      ROS_CI_DESKTOP: "`lsb_release -cs`"  # e.g. [trusty|xenial|...]
      ROS_DISTRO: noetic
    steps:
      - uses: actions/checkout@v2
      - name: Install Non-ROS Dependencies
        run: |
            ls -l $GITHUB_WORKSPACE
            sudo apt-get install -y frei0r-plugins-dev
      - name: Install ROS
        run: |
            sudo sh -c "echo \"deb http://packages.ros.org/ros/ubuntu $ROS_CI_DESKTOP main\" > /etc/apt/sources.list.d/ros-latest.list"
            sudo apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
            sudo apt-get update -qq
            sudo apt-get install dpkg
            sudo apt-get install -y python3-catkin-pkg
            sudo apt-get install -y python3-catkin-tools
            sudo apt-get install -y python3-osrf-pycommon
            sudo apt-get install -y python3-rosdep
            sudo apt-get install -y python3-wstool
            sudo apt-get install -y ros-cmake-modules
            sudo apt-get install -y ros-$ROS_DISTRO-catkin
            source /opt/ros/$ROS_DISTRO/setup.bash
      - name: Install ROS packages with rosdep
        run: |
          source /opt/ros/$ROS_DISTRO/setup.bash
          sudo rosdep init
          rosdep update
          mkdir -p ~/catkin_ws/src
          ln -s $GITHUB_WORKSPACE ~/catkin_ws/src/frei0r_image
          cd ~/catkin_ws
          rosdep install --from-paths src --ignore-src -r -s  # do a dry-run first
          rosdep install --from-paths src --ignore-src -r -y
      - name: catkin build
        run: |
          source /opt/ros/$ROS_DISTRO/setup.bash
          cd ~/catkin_ws
          catkin build --no-status
          source devel/setup.bash
      - name: lint
        run: |
          cd ~/catkin_ws
          catkin build frei0r_image --no-deps --catkin-make-args roslint

It would be fantastic if there was a ubuntu-20.04 target image that already has noetic on it to speed up the build. (In other contexts I've seen downloading a large custom pre-installed image is slower than starting with a clean base image and installing everything from highly available apt repos, but I'm sure that can vary wildly).