ci: update actions/checkout in GitHub Actions workflows to v4

[striezel]

Description

This updates actions/checkout to v4, it's current version.

Changelog:

v4.1.0

• Add support for partial checkout filters

v4.0.0

• Support fetching without the --progress option
• Update to node20

Tasklist

• Ensure all CI builds pass
• Review and approve

[striezel]

This seems to fail on all the jobs using the ubuntu:18.04 Docker container image. :(

[mloskot]

Yeah, this looks like a known issue for Ubuntu 18.04 which is incompatible with Node required by the checkout v4 action:

• NodeJS upgrade breaks ubuntu 18.04 because of GLIBC 2.28 actions/checkout#1442 (comment)
• checkout@v4 doesnt work inside container action actions/checkout#1474

I can't see what can be done about it, other than postpone v3 to v4 pgrade or remove the jobs based on Ubuntu 18.04 (losing GCC 6, Clang 3.9, 4.0 and 5.0).

[striezel]

I can't see what can be done about it, other than postpone v3 to v4 pgrade or remove the jobs based on Ubuntu 18.04 (losing GCC 6, Clang 3.9, 4.0 and 5.0).

I am not sure that losing those CI jobs is acceptable. So I decided not to update the workflows that contain containerized builds to to actions/checkout@v4 and just update the others instead. It may not be the ideal solution, but it's better than nothing, and the jobs should pass now - again.

[mloskot]

Thank you @striezel

Another workaround could be to split this posix job

gil/.github/workflows/ci.yml

Lines 16 to 24 in e24c87f

	posix:
	strategy:
	fail-fast: false
	matrix:
	include:
	- toolset: gcc-6
	cxxstd: "14,1z"
	os: ubuntu-latest
	container: ubuntu:18.04

into posix and posix-legacy, and move 18.04-based builds to the later, then the posix could be upgraded to checkout@v4.

This would mean copying some YAML boilerplate, but I personally don't die hard for DRY in YAML-s :)

[striezel]

That split would make the YAML file even longer and more complicated than it is now. I don't feel that actions/checkout@v3 vs. v4 is such a big improvement that it is worth the effort to make the CI configuration more complicated and maintain two copies of basically the same CI steps.

[mloskot]

Sure. By the way, I kind of steal that from Peter Dimov's https://github.com/boostorg/mp11/blob/develop/.github/workflows/ci.yml 😊

[mloskot]

Thanks @striezel