[libadwaita] Remove usage of gui_app in executable

[Alexander Mikhaylenko <alexm src gnome org>]

commit a365f098b430e57898ccf2e941e0dcec32552b66
Author: Tristan Partin <tristan partin io>
Date:   Wed Oct 27 11:42:06 2021 -0500

    Remove usage of gui_app in executable
    
    This was deprecated a few meson versions ago.

 demo/meson.build | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/demo/meson.build b/demo/meson.build
index 5cd05f0e..90e07d3a 100644
--- a/demo/meson.build
+++ b/demo/meson.build
@@ -24,7 +24,6 @@ adwaita_demo_sources = [
 adwaita_demo = executable('adwaita-@0@-demo'.format(apiversion),
   adwaita_demo_sources,
   dependencies: libadwaita_dep,
-  gui_app: true,
   install: true,
 )