Docker build failures don't propagate

[mattgodbolt]

e.g. this tinycc build failure: https://github.com/compiler-explorer/compiler-workflows/runs/4159648363?check_suite_focus=true

[kasperk81]

workflows pages are showing this warning:

lets see if a comment counts as "activity"

[kasperk81]

lets see if a comment counts as "activity"

no. maybe it'd be enough to commit something from a workflow to avoid it? like amend HEAD commit and force push

cron: "3 2 1 * *" # once a month