fpm has had multiple Ruby gem dependency issues, and nfpm has better support
for code signing if we wanted to do that in the future. The rest of the
platforms may be migrated to nfpm later.
Ubuntu 20 builds were switched to the default reference BLAS because
of a bug with the OpenBLAS package. That bug does not seem to affect
Ubuntu 22, so switch back to using OpenBLAS for Ubuntu 22, for
consistency with all other R builds.
