[gnome-calendar/gnome-3-26] flatpak: Use stable runtime

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit e035beecef06707d39685da3e571cc91527bf25a
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Tue Jan 16 08:51:30 2018 -0200

    flatpak: Use stable runtime

 org.gnome.Calendar.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/org.gnome.Calendar.json b/org.gnome.Calendar.json
index 78107bba..6cf6d2b2 100644
--- a/org.gnome.Calendar.json
+++ b/org.gnome.Calendar.json
@@ -1,7 +1,7 @@
 {
     "app-id": "org.gnome.Calendar",
     "runtime": "org.gnome.Platform",
-    "runtime-version": "master",
+    "runtime-version": "3.26",
     "sdk": "org.gnome.Sdk",
     "command": "gnome-calendar",
     "tags": ["devel"],