Download the released rover_runtime tarballs for the current @version and
write their sha256 checksums to checksum-rover_runtime.exs.
Run this after the release.yml build matrix has attached the per-target
tarballs to the GitHub release (see UPDATE_PROCEDURE.md). The :rover_download
compiler verifies downloads against the file this produces.
mix rover.runtime.download --all --printOptions:
--all— fetch every supported target (default: just the host target)--print— also print the generated checksum map to stdout