Changed duration value to a floating point number per spec 🕙

Author: triplingual

recipe/0489-multimedia-canvas/manifest.json

@@ -9,7 +9,7 @@
         "type": "Canvas",
         "height": 31722,
         "width": 70399,
-        "duration": 180,
+        "duration": 180.0,
         "items": [
           {
             "id": "{{ id.path }}/page/p1/1",