title: Does zef recognize and handle pre-release modules?
body: <p>I have a module <a href="https://gitlab.com/tyil/perl6-app-assixt/" rel="noreferrer"><code>App::Assixt</code></a>, to which I've recently made a relatively large change. I've of course tested it on my local system, but would like to give it some field testing before calling it a "stable release".</p>
  
  <p>Is there a way to "tag" this release as an "alpha", or "release-candidate", so this release will only be installed by people who have opted to use unstable/testing releases?</p>