Fix unnecessary GitHub Actions version specificity and update to modern GitHub Pages deployment

[PathogenDavid]

Before merging this PR: Go to the GitHub Pages settings for this repo and change the build/deployment source to "GitHub Actions".

---

This PR removes unnecessary version specificity for actions used in GitHub Actions workflows in this repository. This reflects best practices and avoids upcoming issues with actions/setup-dotnet, see this issue for details.

While I was at it I migrated the docs workflow to use the modern method for GitHub Pages deployment, and updated other actions as appropriate.

[bparks13]

@PathogenDavid @glopesdev I did not realize that this was still an active repo. We have moved the documentation site to https://github.com/open-ephys/bonsai-onix1-docs and no longer need to keep this one. If you could remove it or archive it as you see fit that would be greatly appreciated!

[PathogenDavid]

Ah, the thought crossed my mind that this might be a dead repo but I was in the flow of doing mass PRs and didn't stop to finish the thought. Archiving this repo with a link to the new repo definitely sounds appropriate.

Edit: We should also probably either add a banner to the website or just blanket redirect all pages to https://open-ephys.github.io/bonsai-onix1-docs/ as well.

[glopesdev]

@PathogenDavid @bparks13 thanks for flagging this. I don't think this repo was ever meant for public consumption anyway, so I will just disable pages and archive the repo.