On RHEL a pre-compiled version is currently installed from the
vendor directory (see the README.md there). On Fedora it is
packaged in podman-plugins and that used to be installed
without explicitly asking for it, but that seems to have changed.
Explicitly install it on Fedora to ensure it is present.
Symptom of the dns plugin missing is that the koji hub container
will not start because it will block waiting for the postgres
container forever.