Update GitHub Actions workflows to upstream latest versions

[nanxstats]

This PR updates all GitHub Actions workflows to their latest versions from upstream (r-lib/actions).

The upstream changes mostly involves updating actions/checkout and actions/upload-artifact to v4, which updated the default runtime to Node.js 20.

I just ran

usethis::use_github_action("check-standard")
usethis::use_github_action("pkgdown")
usethis::use_github_action("test-coverage")
usethis::use_github_action("style")

Also, this fixes #213.

[nanxstats]

The segmentation fault you see in macOS is similar to tidyverse/dplyr#6961. Not related to the PR.

[nanxstats]

I created an issue on a possible cause after looking into the problematic test file: #213 Not entirely sure if it's relevant.

[nanxstats]

OK, here is what I found and did to improve the testing situation, now this is ready:

• Removing the unnecessary svg() and dev.off() calls (dbb3c03) resolved the macOS segmentation fault. This is the culprit.

• I further removed the library() calls from tests/testthat.R, individual tests, and qualified the involved namespaces in tests (7896111) following the standard.

• Additionally, I used the testthat native mechanism skip_if_not_installed() to replace requireNamespace() in the tests driven by officer (f808ad1).