[gnome-builder] flatpak: update nightly URL

[Christian Hergert <chergert src gnome org>]

commit 29668106f1f7bd5ddbf8985bd08952d30ef658bb
Author: Christian Hergert <chergert redhat com>
Date:   Tue Oct 1 12:03:56 2019 -0700

    flatpak: update nightly URL

 src/plugins/flatpak/gbp-flatpak-application-addin.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/plugins/flatpak/gbp-flatpak-application-addin.c 
b/src/plugins/flatpak/gbp-flatpak-application-addin.c
index 41468475a..7ac854dd4 100644
--- a/src/plugins/flatpak/gbp-flatpak-application-addin.c
+++ b/src/plugins/flatpak/gbp-flatpak-application-addin.c
@@ -101,7 +101,7 @@ static GbpFlatpakApplicationAddin *instance;
 static guint signals [N_SIGNALS];
 static BuiltinFlatpakRepo builtin_flatpak_repos[] = {
   { "flathub",       "https://flathub.org/repo/flathub.flatpakrepo"; },
-  { "gnome-nightly", "https://sdk.gnome.org/gnome-nightly.flatpakrepo"; },
+  { "gnome-nightly", "https://nightly.gnome.org/gnome-nightly.flatpakrepo"; },
 };
 
 static void gbp_flatpak_application_addin_lazy_reload (GbpFlatpakApplicationAddin *self);