Upgrade GitHub Actions checkout and setup-node on 4.x branch

[cclauss]

Like #2024 but on another branch.

• https://github.com/actions/checkout/releases
• https://github.com/actions/setup-node/releases

Removes the depreciation errors like at https://github.com/handlebars-lang/handlebars.js/actions/runs/6997734302

Before creating a pull-request, please check https://github.com/handlebars-lang/handlebars.js/blob/master/CONTRIBUTING.md first.

Generally we like to see pull requests that

• Please don't start pull requests for security issues. Instead, file a report at https://www.npmjs.com/advisories/report?package=handlebars
• Maintain the existing code style
• Are focused on a single change (i.e. avoid large refactoring or style adjustments in untouched code if not the primary goal of the pull request)
• Have good commit messages
• Have tests
• Have the typings (types/index.d.ts) updated on every API change. If you need help, updating those, please mention that in the PR description.
• Don't significantly decrease the current code coverage (see coverage/lcov-report/index.html)
• Currently, the 4.x-branch contains the latest version. Please target that branch in the PR.