Fix GitHub Actions warnings

[krazkidd]

The following warnings appear on the most recent run of the GitHub Pages workflow:

Warning

build
Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions/setup-node@v3, actions/configure-pages@v3, actions/cache@v3, actions/upload-artifact@v3. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

Warning

build
Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/deploy-pages@v2. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

Warning

Deprecation notice: v1, v2, and v3 of the artifact actions
The following artifacts were uploaded using a version of actions/upload-artifact that is scheduled for deprecation: "github-pages".
Please update your workflow to use v4 of the artifact actions.
Learn more: https://github.blog/changelog/2024-04-16-deprecation-notice-v3-of-the-artifact-actions/