gst: use theora in the test pipeline.
gst: use theora in the test pipeline.

AnilRamachandran/aravis,AravisProject/aravis,AnilRamachandran/aravis,lu-zero/aravis,AravisProject/aravis,AravisProject/aravis,AnilRamachandran/aravis,lu-zero/aravis,AravisProject/aravis,AnilRamachandran/aravis,AnilRamachandran/aravis,lu-zero/aravis,AravisProject/aravis,lu-zero/aravis,lu-zero/aravis