This fixes a few issues with swaybar's cursor scaling:
1. The cursor scale is now changed when the output scale changes
2. The cursor scale is no longer bound by the max output scale when
swaybar is launched
3. Related to the previous item, the cursor is no longer tiny on low
scale outputs after the max output scale has changed
This also bumps up `wl_compositor` to version 4 to allow usage of
`wl_surface_damage_buffer`.
