How To: Make libffi6 work with Github actions and Ubuntu 22.04 and Ubuntu 20.04

A few days ago my Github Action for rt-kits-api3 broke because the default operating system for ubuntu-latest changed to 22.04.1 from 18.04
The easy way to fix this was to change ubuntu-latest to ubuntu-18.04 but that will break in April 2023.
The proper way to fix it for now until the ruby ffi gem is fixed to work with libffi7 is to install libffi6 (alongside libffi7; libffi6 is not part of Ubuntu 22.04 and 20.04 by default) manually using the following yaml in the Github Actions file:

- name: Install libffi6
      run: |-
        curl -LO http://archive.ubuntu.com/ubuntu/pool/main/libf/libffi/libffi6_3.2.1-8_amd64.deb
        sudo dpkg -i libffi6_3.2.1-8_amd64.deb

There has to be a better way :-) but I couldn’t find one! Maybe upgrading to Ruby 3.x from 2.7.x would fix it?
For full details, see: fix libffi7 issue before March 2023 when ubuntu 18.04 is deprecated #2

Previously

March 13, 2022: Free computing e.g. at github actions isn’t free; free cloud computing considered harmful (because environment: see Steven Gonzalez Monserrate January 27, 2022: The Cloud Is Material: On the Environmental Impacts of Computation and Data Storage via The Staggering Ecological Impacts of Computation and the Cloud via Kottke
March 14, 2021: On March 3, 2021 Github action in rt-kits-api3 to get Firefox support questions broke because ruby gem ffi-1.13.1 wasn’t found, fix:change Gemfile ffi version to 1.15.0
October 18, 2020: Github Actions are super powerful and yaml is super confusing