make ignoring github pre-releases optional #327

Or perhaps (for less breaking), make including pre-releases optional?

Something like this:

versions:
    github: org/repo/releases
    strip: /v/
    prerelease: true # this

Or, maybe an additional /pre-releases option?
Like:

versions:
    - github: org/repo/pre-releases
      strip: /v/
    # If they release any proper (stable) version, it'd match that as well.
    - github: org/repo/releases
      strip: /v/

Exactly. include-prereleases: bool? was what I was thinking.

Really we should build them and then have pkgx ignore them by default. If they don’t build then we discard that release because we don't care much.