Update Flatpak runtime

Author: johnfactotum

com.github.johnfactotum.Foliate.json

@@ -1,7 +1,7 @@
 {
     "app-id" : "com.github.johnfactotum.Foliate",
-    "runtime" : "org.gnome.Platform",
-    "runtime-version" : "45",
+    "runtime" : "org.gnome.Sdk",
+    "runtime-version" : "47",
     "sdk" : "org.gnome.Sdk",
     "command" : "foliate",
     "finish-args" : [