Unbind from room values when disposing

osu.Game/Screens/Multiplayer/DrawableRoom.cs

@@ -245,5 +245,15 @@ private void displayBeatmap(BeatmapMetadata value)
                 beatmapArtist.Text = string.Empty;
             }
         }
+
+        protected override void Dispose(bool isDisposing)
+        {
+            Room.Name.ValueChanged -= displayName;
+            Room.Host.ValueChanged -= displayUser;
+            Room.Status.ValueChanged -= displayStatus;
+            Room.Beatmap.ValueChanged -= displayBeatmap;
+
+            base.Dispose(isDisposing);
+        }
     }
 }