[gnome-contacts] flatpak: use main branch for libportal

[Jeremy Bicha <jbicha src gnome org>]

commit 0ace246fe000474bf3bc109affcd030dad62c016
Author: Jeremy Bicha <jeremy bicha canonical com>
Date:   Wed Mar 2 18:29:29 2022 +0100

    flatpak: use main branch for libportal

 build-aux/flatpak/org.gnome.Contacts.Devel.json | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/build-aux/flatpak/org.gnome.Contacts.Devel.json b/build-aux/flatpak/org.gnome.Contacts.Devel.json
index e6d7f2b5..61a26d28 100644
--- a/build-aux/flatpak/org.gnome.Contacts.Devel.json
+++ b/build-aux/flatpak/org.gnome.Contacts.Devel.json
@@ -164,6 +164,7 @@
                 {
                     "type" : "git",
                     "url" : "https://github.com/flatpak/libportal.git";
+                    "branch" : "main"
                 }
             ]
         },