This adds wlr_seat_touch_notify_cancel() to be used by compositors to cancel touch gestures.
(cherry picked from upstream commit 17b2b06633729f1826715c1d0b84614aa3cedb3a)
With this https://gitlab.gnome.org/World/Phosh/phoc/-/merge_requests/346 becomes more useful.
This also includes the updated d/changelog to avoid another round trip.