temp/gtk+3.0: Fix Phosh boot splash

For the splash screen to correctly dismiss itself without hitting the timeout, we need a Gtk patch.

This is described in the Phosh release notes: https://gitlab.gnome.org/World/Phosh/phosh/-/releases/v0.30.0#required-patches-that-arent-merged-upstream-yet

The patch isn't in upstream yet, but there is an open PR: https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/5628

Mobian also carries the patch: https://salsa.debian.org/Mobian-team/packages/gtk3/-/blob/mobian/debian/patches/purism/gdk-wayland-Track-last-touch-serial-on-seat.patch

So let's add the patch to pmOS as well. This fixes the Phosh splash screens so they now disapear when the application is ready.