* Download the repo using actions/checkout (so the latest ref is always referenced, without the need of hacky env vars).
The .tar file is created after the repo is cloned, so it can be reused for every step (instead of wget'ting it at every step).
This should reduce the possibility of timeouts or other network errors.
* Action can now run on private repos
* Reduced verbosity of tar: The -v argument is not that necessary in this kind of context,
where the contents of the archive will always be predictable.
627d60b965