Build/Test Tools: Update some third-party GitHub Actions.

This updates the following GitHub Actions:
- `actions/cache` from `5.0.3` to `5.0.4`
- `codecov/codecov-action` from `5.5.2` to `5.5.3`

This resolves the final `node20`-related deprecation notices being triggered by GitHub Actions.

See #64227.

git-svn-id: https://develop.svn.wordpress.org/trunk@62053 602fd350-edb4-49c9-b593-d223f7449a82