Enable local file access for imgkit.

See https://stackoverflow.com/questions/62315246/wkhtmltopdf-0-12-6-warning-blocked-access-to-file

app.py

@@ -252,7 +252,7 @@ def html_to_png(card_name, html):
     try:
         css = ['./css/mana.css', './css/keyrune.css',
                './css/mtg_custom.css']
-        imgkit.from_string(html, path, {"xvfb": ""}, css=css)
+        imgkit.from_string(html, path, {"xvfb": "", "enable-local-file-access": ""}, css=css)
     except Exception as e:
         print("ImgKit Error:")
         print(e)