[gtkmm] Use gtk4 from the main branch in subproject

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 9c326b3aee94d99abf9d6f6431601b7ad2d12a47
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Tue Feb 1 09:04:10 2022 +0100

    Use gtk4 from the main branch in subproject

 subprojects/gtk4.wrap | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/subprojects/gtk4.wrap b/subprojects/gtk4.wrap
index 66e73ea9..b5e45c41 100644
--- a/subprojects/gtk4.wrap
+++ b/subprojects/gtk4.wrap
@@ -1,7 +1,7 @@
 [wrap-git]
 directory=gtk
 url=https://gitlab.gnome.org/GNOME/gtk.git
-revision=master
+revision=main
 depth=1
 
 [provide]