[gnome-nibbles/arnaudb/wip/gtk4] Try to fix CI.

[Arnaud B. <arnaudb src gnome org>]

commit 7a17ee000efc861a0ef9ce8c3630648dc12580ee
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Tue Jun 16 18:35:17 2020 +0200

    Try to fix CI.

 org.gnome.Nibbles.json | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/org.gnome.Nibbles.json b/org.gnome.Nibbles.json
index 124f894..d2bda47 100644
--- a/org.gnome.Nibbles.json
+++ b/org.gnome.Nibbles.json
@@ -50,6 +50,7 @@
         {
             "name": "libgnome-games-support",
             "buildsystem": "meson",
+            "branch": "arnaudb/wip/gtk4",
             "sources": [
                 {
                     "type": "git",
@@ -60,6 +61,7 @@
         {
             "name": "gnome-nibbles",
             "buildsystem": "meson",
+            "branch": "arnaudb/wip/gtk4",
             "sources": [
                 {
                     "type": "git",