[gnome-tweaks/gnome-40] Use `HEAD` instead of `main` in GNOME Extensions link

[Evan Welsh <ewlsh src gnome org>]

commit a039a708e033c68716ec4e8643e04c8c09c19c1d
Author: Evan Welsh <contact evanwelsh com>
Date:   Sun Oct 31 01:37:34 2021 +0000

    Use `HEAD` instead of `main` in GNOME Extensions link
    
    `HEAD` will survive branch renames

 gtweak/app.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtweak/app.py b/gtweak/app.py
index b1afe2f..64bb250 100644
--- a/gtweak/app.py
+++ b/gtweak/app.py
@@ -27,7 +27,7 @@ class ExtensionNotice(Gtk.MessageDialog):
             "{0}\n\n{1}".format(
                 # Translators: Placeholder will be replaced with "GNOME Extensions" in active link form
                 _("Extensions management has been moved to {0}.").format(
-                    '<a 
href="https://gitlab.gnome.org/GNOME/gnome-shell/-/blob/main/subprojects/extensions-app/README.md";>GNOME 
Extensions</a>',
+                    '<a 
href="https://gitlab.gnome.org/GNOME/gnome-shell/-/blob/HEAD/subprojects/extensions-app/README.md";>GNOME 
Extensions</a>',
                 ),
                 # Translators: Placeholder will be replaced with "Flathub" in active link form
                 _("We recommend downloading GNOME Extensions from {0} if your distribution does not include 
it.").format(