temp/gtk4.0: fix Plasma Mobile virtual keyboard not opening on GTK apps (MR 3181)

pmOS equivalent of https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/34970

temp/gtk4.0/APKBUILD

@@ -3,7 +3,7 @@
 pkgname=gtk4.0
 pkgver=9999
 _pkgver=4.6.4
-pkgrel=1
+pkgrel=2
 pkgdesc="The GTK Toolkit (v4)"
 url="https://www.gtk.org/"
 install="$pkgname.post-install $pkgname.post-upgrade $pkgname.post-deinstall"

temp/gtk4.0/gtk4.0.post-install

 #!/bin/sh
 
-mkdir -p etc/gtk-4.0
-usr/bin/gdk-pixbuf-query-loaders > etc/gtk-4.0/gdk-pixbuf.loaders
-
+/usr/bin/gdk-pixbuf-query-loaders --update-cache