To avoid Actions core deprecation messages.

https://github.com/actions/publish-action/releases/tag/v0.2.1

Node.js 12 actions are deprecated as of 27/9/2022. Only Node.js 16 is supported for actions.

…ease-process

the `record_expected_output` script now uses the `act` utility
(https://github.com/nektos/act) to run this repo's action in a container
as github actions would.

You can now pass one argument to that, `local`, to go back to running
`github-pages` on your local ruby install. (I removed the `.ruby-version`
file since we don't *need* to record using the local env anymore, so
make sure that you're on Ruby 2.7.4)

This eliminates the inconsistency between recorded output and generated
output on actions, so we don't need to ignore any lines in `diff` anymore.

There is no expected output committed to the repo yet, so it is expected
to fail.

Add jekyll-octicons to published image