[calls] d/gbp.conf: Set default branch to 'main' (was 'master')

[Guido Günther <guidog src gnome org>]

commit 396152bd245bfe3e57f918ac623e3ae820541e9f
Author: Evangelos Ribeiro Tzaras <devrtz fortysixandtwo eu>
Date:   Thu Sep 1 19:45:12 2022 +0200

    d/gbp.conf: Set default branch to 'main' (was 'master')
    
    The default branch of Calls has switched to 'main'.
    
    See #490

 debian/gbp.conf | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/debian/gbp.conf b/debian/gbp.conf
index e57ef6ae..3a67b2ae 100644
--- a/debian/gbp.conf
+++ b/debian/gbp.conf
@@ -1,5 +1,5 @@
 [DEFAULT]
-debian-branch = master
+debian-branch = main
 debian-tag = v%(version)s
 debian-tag-msg = GNOME Calls v%(version)s