Migrate the Github Actions to the new YAML syntax

[youknowriad]

I just used the Github tool to migrate our Github actions workflows to the new yaml syntax.

[senadir]

since it was done by an automated tool i don't think there should be any problems, and I don't think we can test it before merge, so all good i guess.

[ntwb]

I guess the updated actions don't work on the actual PR making the change 😏

Merge away and see what happens next PR :yolo:

[youknowriad]

Let's see :P

[ntwb]

@youknowriad lol, and, nope, no actions queued on the #16985 PR

[senadir]

a lot of them did in #16984

[ntwb]

Hehehehe, so no change in behavior of the actions then ;)

[noisysocks]

I think @talldan convinced me that all our project automation actions should be in one workflow. We should also look into making them JavaScript-based instead of Docker-based. I might have a play with it on Wednesday 🙂

[talldan]

I was thinking about this as a way to reduce the amount of checks in PRs by a factor of 3.

However, I just noticed when I went to the 'actions' tab in Github (https://github.com/WordPress/gutenberg/actions), that a little popup showed up asking me if I wanted to enable the new actions from this PR. I clicked enable. Let's see if that makes a difference. (edit: Yep, looks like it has migrated us over to the new logging - https://github.com/WordPress/gutenberg/pull/16957/checks?check_run_id=190959011)

[youknowriad]

We should rename the checks titles to be smaller :)

[talldan]

I've spotted some issues. It looks like exit code 78 isn't supported any more by actions—created PR #17002, but the filter we're using also uses 78, so still seeing checks failing.

Multiple checks are still showing. The logging shows that actions are being triggered multiple times for any of the following things that can happen to a PR:
assigned, unassigned, labeled, unlabeled, opened, edited, closed, reopened, synchronize, ready_for_review, locked, unlocked

Yet to discover if there's a way to improve this.