[glibmm] Use GLib from the main branch in subproject

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 2ec1b1fe502b5816bb4abef038a3e2eea9976f2c
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Sat Jul 31 12:16:36 2021 +0200

    Use GLib from the main branch in subproject

 subprojects/glib.wrap | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/subprojects/glib.wrap b/subprojects/glib.wrap
index a6827389..bcac8786 100644
--- a/subprojects/glib.wrap
+++ b/subprojects/glib.wrap
@@ -1,7 +1,7 @@
 [wrap-git]
 directory=glib
 url=https://gitlab.gnome.org/GNOME/glib.git
-revision=master
+revision=main
 depth=1
 
 [provide]