[gnome-builder/wip/gtk4-port] build: add d-spy to dependencies

[Christian Hergert <chergert src gnome org>]

commit 0f200e0b4c755c5f360eaaee561285abd0cd5817
Author: Christian Hergert <chergert redhat com>
Date:   Tue Apr 19 16:47:46 2022 -0700

    build: add d-spy to dependencies

 build-aux/flatpak/org.gnome.Builder.json | 11 +++++++++++
 1 file changed, 11 insertions(+)
---
diff --git a/build-aux/flatpak/org.gnome.Builder.json b/build-aux/flatpak/org.gnome.Builder.json
index 434a6da2c..b08849a26 100644
--- a/build-aux/flatpak/org.gnome.Builder.json
+++ b/build-aux/flatpak/org.gnome.Builder.json
@@ -749,6 +749,17 @@
                 }
             ]
         },
+        {
+            "name" : "d-spy",
+            "buildsystem" : "meson",
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/d-spy.git";,
+                    "branch" : "main"
+                }
+            ]
+        },
         {
             "name" : "gnome-builder",
             "buildsystem" : "meson",