audio/sayonara: enable PulseAudio, repair Python scripts

Sayonara did not have a dependency on GStreamer PulseAudio plugins,
so it would use only ALSA for output. PA is installed anyway in
desktop systems, so enable the plugin. Thanks Harald for the
simple patch.

While here, repair the Python scripts, which need pydbus --
add the dependency, then repair the code to work with the
version of pydbus that we have in ports.

Reported-by: Harald Schmalzbauer <bugzilla.freebsd@omnilan.de>
PR: 279568