Update app.py

app.py

@@ -11,6 +11,7 @@ with open('./config.yaml', 'r') as fd:
 sys.path.insert(0, './white_box_cartoonizer/')
 
 import cv2
+from markupsafe import Markup
 from flask import Flask, render_template, make_response, flash
 import flask
 from PIL import Image