Update GitHub Actions to use the Node 20 actions

[sadukie]

As seen in the CI/CD:

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v2, technote-space/toc-generator@v4. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

• Update checkout to v4 (I've done this on other projects, so I can confirm this is the correct version.)
• Update technote-space/toc-generator to its Node 20 version if available.

[KyleMcMaster]

Reopened since technote-space/toc-generator has not been updated yet