Use GitHub Actions for building the project

[jurica]

See the discussion here: #405 (reply in thread)

It would be nice to use GitHub Actions for building and releasing zk.

Goals

• build linux binaries on actions
• build macOS binaries on actions
• build Windows binaries on actions
• build src tarball on actions

[jurica]

Just a short update: I didn't forget about this, but apart from some research and local tests haven't done anything more yet. I think that during summer I unfortunately will not find a lot of spare time to spend for doing serious work here. But definitively want to tackle it once the evenings start getting longer and the weather starts getting worse. ;)

[tjex]

Not a prob. Thanks for the update.