img mock update

(cherry picked from commit 7c43951)

Author: monfera

test/image/mocks/table_plain_birds.json

@@ -14,7 +14,7 @@
             "y": [0, 1]
         },
 
-        "columnwidth": [20, 40, 25, 25, 30, 20, 30],
+        "columnwidth": ["20", "40", "25", "25", "30", "20", "30"],
         "columnorder": [0, 1, 2, 3, 4, 5, 6],
 
         "header": {