Instead of manually specifying a list of Fedora versions to target, we
can now use the `fedoraBuild` pipeline function to generate the target
matrix automatically.
Note that the stage names need to be unique, as the `when` function
cannot mark the correct stage as "skipped" if there are multiple stages
with the same name.
It turns out, everything is already in place to enable kernel module
signing. All that's necessary is to provide a certificate and private
key at the correct path; if those are present, the modules files will be
signed during `modules_install`.
