[scrobbles] Fix look up of old scrobbles by total seconds

vrobbler/apps/scrobbles/models.py

@@ -822,7 +822,7 @@ class Scrobble(TimeStampedModel):
         """
         is_stale = False
         now = timezone.now()
-        seconds_since_last_update = (now - self.modified).seconds
+        seconds_since_last_update = (now - self.modified).total_seconds()
         if seconds_since_last_update >= self.media_obj.SECONDS_TO_STALE:
             is_stale = True
         return is_stale