Caching of Build Artifacts

[vbrandl]

I'm not sure if this is actually possible with GitHub Actions (yet?) but it would be cool to be able to cache the target directory between builds for some speedups.

[svartalf]

Based on the actions/toolkit#47, it is not possible yet (and it is very unfortunate).

Let's leave this issue opened and pretend it to be a tracking issue for caching support.

[Hoverbear]

https://github.com/actions/cache was released recently! :)