Update supported Node versions for JavaScript Composite Actions

[louis-bompart]

Describe the enhancement
Currently, JavaScript composite actions only support Node 12 and 16.
Node 12 is deprecated and Node 16 has an accelerated EoL. So arguably, none are viable choices for long-term development.

I would propose removing support for Node 12 and adding support for 18 (current Active LTS).

[louis-bompart]

I did not know of https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/ prior to opening this issue & #2257

Even if forcing the move to Node16 is a good idea, if it's done for the 1st day of Summer, it will give users less than a quarter with a maintained NodeJS version.

I understand tho that dropping Node12 so suddenly would be a bit... uncouth. (especially given your prior announcement)

I'd propose adding support for Node18 for now, and instead of "migrate all actions to run on Node16 by Summer 2023.", I think you should skip Node 16 and go straight to 18.

When dropping Node 12 in Summer '23, it'll be interesting to add support for Node 20, given that it'll be the Active LTS just a quarter later.

[fhammerl]

Hello @louis-bompart, thanks for taking an interest in keeping the runner up-to-date.
We internally plan our Node deprecation and upgrade cycle, based mostly on LTS / deadlines.

We bundle all supported Node versions in the release archive, so it's not feasible to add too many newer versions.
We also cannot cut support for Node 12 right now as we have just started deprecating it.

Tentative look to the future: As you know, Node 12 in the runner is being deprecated, I would expect the same time we finally drop it we will introduce a new LTS Node version - likely Node 20.

[brandonchinn178]

@fhammerl now that all the runner images are using Node 18, would it be possible to add Node 18 as an option for Javascript Composite Actions? It'd be really great to get actions/github-script#310

[MikeMcC399]

@fhammerl

You mentioned in #2255 (comment) about supporting node20 for JavaScript actions. Can you confirm if this will be the plan?

Node.js 20 was released today, April 18, 2023 - see Node v20.0.0 (Current).

[MikeMcC399]

Also submitted to https://github.com/orgs/community/discussions/53217

[TomasHubelbauer]

@fhammerl Is there a more concrete date at which we can roughly expect a Node 20 runtime for JavaScript GitHub Actions will be available? The support window for Node 16 is slowly coming to a close and it would be excellent to be able to use a more up to date runtime version in our JavaScript GitHub Actions.

[DariuszPorowski]

JFYI potential ugly temporary workaround for action authors: https://github.com/orgs/community/discussions/53217#discussioncomment-6227341

[MikeMcC399]

• See actions/runner nodejs plan and next steps #2704