GitHub Actions for Test and Release automation

[ingydotnet]

Not too hard. Just need to find the time.

Currently we use personal servers for builds and we might want to continue using them but triggered by GHA.

Will depend on rate limits.

[ingydotnet]

See:

• https://github.com/bpan-org/bpan-index-ingydotnet/blob/main/.github/workflows/bpan-publish.yaml
• https://github.com/borkdude/nbb-action-example