Update github actions to latest versions

[martinling]

• Update actions/checkout from v2/3 to v4
• Update actions/upload-artifact from v2 to v4
  • Avoid conflicting artifacts by uploading only those from the stable Rust build.
• Replace unmaintained actions-rs actions with direct use of rustup and cargo.
• Always use the latest version of the Ubuntu runner.
• Replace deprecated GabrielBB/xvfb-action with direct use of xvfb-run.
• Don't try to install pkg-config on macOS; the runner has it.

[martinling]

I was hoping this would fix the slew of deprecation warnings that show up in each of our CI runs, but it turns out most of those are due to unmaintained actions from the now-archived @actions-rs organisation.

So we need to see about replacing those too.

[miek]

I was hoping this would fix the slew of deprecation warnings that show up in each of our CI runs, but it turns out most of those are due to unmaintained actions from the now-archived @actions-rs organisation.

So we need to see about replacing those too.

I had a look into this as well and couldn't find a solid set of replacement actions. However, it looks like rustup is included in all the runners nowadays, so I'm leaning towards just running that directly.

[martinling]

Yeah, I think actions-rs/toolchain and actions-rs/cargo can be replaced easily by direct use of rustup and cargo.

I'm not sure what to do about actions-rs/clippy-check - there are several forks/successors.

[miek]

I was thinking just run cargo clippy directly too. It seems like the fancy annotations that the action does often fail on PRs anyway & having the normal output from clippy would be more useful.

[martinling]

All done. No more warnings!