[retro-gtk] flatpak: Downgrade the SDK from master to 3.26

[Adrien Plazas <aplazas src gnome org>]

commit c8955ab421d47358e596f10817fbe5292d4e3d46
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Sat Nov 4 07:50:47 2017 +0100

    flatpak: Downgrade the SDK from master to 3.26
    
    This allows to build with the required Meson 0.43.0 as master is lagging
    on that part.

 flatpak/org.gnome.Retro.DemoSamplesTest.json |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/flatpak/org.gnome.Retro.DemoSamplesTest.json b/flatpak/org.gnome.Retro.DemoSamplesTest.json
index f6c12cd..07233ca 100644
--- a/flatpak/org.gnome.Retro.DemoSamplesTest.json
+++ b/flatpak/org.gnome.Retro.DemoSamplesTest.json
@@ -1,7 +1,7 @@
 {
     "app-id": "org.gnome.Retro.DemoSamplesTest",
     "runtime": "org.gnome.Platform",
-    "runtime-version": "master",
+    "runtime-version": "3.26",
     "sdk": "org.gnome.Sdk",
     "command": "retro-demo-samples-test",
     "tags": ["nightly"],