"Container action is only supported on Linux"

[i-make-robots]

error:
https://github.com/MarginallyClever/Makelangelo-firmware/runs/1396963998?check_suite_focus=true#step:6:9

workflow:
https://github.com/MarginallyClever/Makelangelo-firmware/actions/runs/362003308/workflow

[finnp]

This is still based on v1 of github actions. If you or someone is interested, we should rewrite this to not use a docker container: https://docs.github.com/en/free-pro-team@latest/actions/creating-actions/creating-a-composite-run-steps-action