Update actions/setup-node to v4

[trivikr]

changelog: none

Required for using Node.js 20.x in CI

• Changelog for actions/checkout@v4 https://github.com/actions/checkout/blob/main/CHANGELOG.md?rgh-link-date=2024-09-04T18%3A38%3A10Z#v400
• GitHub Blog post https://github.blog/changelog/2024-03-07-github-actions-all-actions-will-run-on-node20-instead-of-node16-by-default/

Example warning: https://github.com/rust-lang/rust-clippy/actions/runs/11003847751

The following actions use a deprecated Node.js version and will be forced to run on node20: actions/setup-node@v3.

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @flip1995 (or someone else) some time within the next two weeks.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

• @rustbot author: the review is finished, PR author should check the comments and take action accordingly
• @rustbot review: the author is ready for a review, this PR will be queued again in the reviewer's queue

[flip1995]

@bors r+

Thanks!

[bors]

📌 Commit f7b940a has been approved by flip1995

It is now in the queue for this repository.

[bors]

⌛ Testing commit f7b940a with merge 26e1660...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: flip1995
Pushing 26e1660 to master...