Bump wayland-protocols requirements

Bump wayland-protocols requirements

The `name` and `description` events were added to `xdg-output` protocol
in version 2 which is part of wayland-protocols 1.14.

In xdg-output-v1 version 3, the `xdg-output.done` event was deprecated
and the `xdg-output.description` event was made mutable, but that
doesn't change the actual events so we do not actually need to require
that version of xdg-output from wayland-protocols 1.18.

Update the wayland-protocols requirement to the bare minimum version,
which is 1.14.

https://gitlab.gnome.org/GNOME/gtk/issues/2057