[gedit] Try to fix flatpak build

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 27b45194cc3dd8a0c7304f66b21c0d44c57eca34
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Tue Aug 6 11:20:05 2019 -0500

    Try to fix flatpak build

 build-aux/flatpak/org.gnome.gedit.json | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/build-aux/flatpak/org.gnome.gedit.json b/build-aux/flatpak/org.gnome.gedit.json
index 0d62fcbb3..711fa3393 100644
--- a/build-aux/flatpak/org.gnome.gedit.json
+++ b/build-aux/flatpak/org.gnome.gedit.json
@@ -40,6 +40,7 @@
     "modules" : [
         {
             "name" : "libpeas",
+            "buildsystem": "meson",
             "cleanup" : [
                 "/bin/*",
                 "/lib/peas-demo"