First release with some prebuilt binaries

I'm just manually downloading and uploading the build artifacts from https://github.com/marler8997/zigup/actions/runs/945339228.

Some things to note

1. it seems to use the .zip format, but we probably want something else for linux/mac (i.e. .tar.xz)
2. Windows is missing since it won't build on CI yet
3. this should be automated somehow, will have to look into it