Output the disc-number

The disc-number was using the wrong field name.

Fixes #25 (closed)

funkwhale_cli/output.py

@@ -38,7 +38,7 @@ FIELDS = {
         "Title": {"field": "title"},
         "Artist": {"field": ["album.artist.name", "track.artist.name"]},
         "Album": {"field": "album.title"},
-        "Disc": {"field": "disc", "handler": lambda v: v or 1},
+        "Disc": {"field": "disc_number", "handler": lambda v: v or 1},
         "Position": {"field": "position"},
     },
     "UPLOAD": {