[d-spy] build: bump GTK requirement

[Christian Hergert <chergert src gnome org>]

commit 25ad6f5b941109f430d80c414bf0c975f9bd7e9d
Author: Christian Hergert <chergert redhat com>
Date:   Fri Mar 18 16:30:48 2022 -0700

    build: bump GTK requirement
    
    Really you need this anyway for proper libadwaita.

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 0e373e9..c8b7379 100644
--- a/meson.build
+++ b/meson.build
@@ -32,7 +32,7 @@ config_h.set_quoted('PACKAGE_WEBSITE', 'https://gitlab.gnome.org/GNOME/d-spy')
 config_h.set10('DEVELOPMENT_BUILD', get_option('development'))
 
 glib_req_version = '2.68'
-gtk_req_version = '4.2'
+gtk_req_version = '4.6'
 adwaita_req_version = '1.0'
 
 glib_req = '>= @0@'.format(glib_req_version)