[gnome-font-viewer] flatpak: revert back to master runtime

[Cosimo Cecchi <cosimoc src gnome org>]

commit 8cccc7dd85b27a69f8df01c2b58dfa69ff8f3df2
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Sat Jul 6 09:49:05 2019 -0700

    flatpak: revert back to master runtime
    
    This should make the CI work again.

 flatpak/org.gnome.font-viewer.json | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/flatpak/org.gnome.font-viewer.json b/flatpak/org.gnome.font-viewer.json
index 07a40d1..1b50f30 100644
--- a/flatpak/org.gnome.font-viewer.json
+++ b/flatpak/org.gnome.font-viewer.json
@@ -2,7 +2,6 @@
     "app-id": "org.gnome.font-viewer",
     "runtime": "org.gnome.Platform",
     "sdk": "org.gnome.Sdk",
-    "runtime-version": "3.32",
     "command": "gnome-font-viewer",
     "finish-args": [
         "--device=dri",