Bump actions/{checkout, cache} version to v4

[devreal]

See https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/

Bumping the action/checkout version should fix these warnings:

macos-latest: clang++ Release
The following actions uses node12 which is deprecated and will be forced to run on node16: actions/checkout@v2, actions/[email protected]. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/