Add spotify queue

spotify.py

@@ -186,6 +186,12 @@ class SpotifyClient:
         playback() first rather than pausing on spec."""
         self._call("PUT", "/v1/me/player/pause")
 
+    def queue(self) -> list:
+        """What this account plays next, in order: whatever was queued by
+        hand first, then the rest of the album or playlist. Spotify sends
+        one page of it, about twenty items, and has no way to ask for fewer."""
+        return self._call("GET", "/v1/me/player/queue").get("queue") or []
+
     def seek(self, position_ms: int):
         """Jump to position_ms in whatever the account is playing, on
         whichever device is playing it."""