Set up CI

[dslmeinte]

Use GitHub Actions.

1. Build
2. Test
3. Publish to nuget.org
4. Reserve prefix; see: https://learn.microsoft.com/en-us/nuget/nuget-org/id-prefix-reservation?WT.mc_id=DT-MVP-5003978

[dslmeinte]

Now using:

• https://www.meziantou.net/publishing-a-nuget-package-following-best-practices-using-github.htm
• https://docs.github.com/en/actions/using-workflows/about-workflows

Items 1 and 2 done — item 3 not yet; put that in a separate YAML file?

[dslmeinte]

TODOs for item 3:

1. Create API key
2. Publish a new version manually using that key
3. Do the same via a GitHub Action
4. Properly Refactor the GitHub Actions so that release is triggered from a tag, and other commits just trigger build+test

[dslmeinte]

All done through PR #8