cerbero/oven: propagate skip to the tasks
cerbero/oven: propagate skip to the tasks

Fixes https://gitlab.freedesktop.org/gstreamer/cerbero/issues/253

GStreamer/cerbero,nirbheek/cerbero,GStreamer/cerbero,nirbheek/cerbero,GStreamer/cerbero,nirbheek/cerbero,GStreamer/cerbero,nirbheek/cerbero,GStreamer/cerbero