Show volume notification even when attempting to raise the volume while it's already at maximum

The volume notification appears whenever the volume is changed. If the volume is already at maximum, trying to raise the volume will not show the notification. It could be more user-friendly if it showed the notification even if the volume was already at maximum when raising it. And likewise for minimum volume. This is the behavior that volumeicon already has.

Reddit discussion: https://www.reddit.com/r/xfce/comments/mhiqpb/showing_volume_slider_at_max_volume_using/