Update app.py to support port 80 and EC2 deployment

Author: EC2 Default User

backend/app.py

@@ -136,6 +136,6 @@ def predict():
         forecast=result,
         plot_url="/static/plot.png"
     )
-
 if __name__ == "__main__":
-    app.run(debug=True)
+    app.run(host="0.0.0.0", port=80, debug=True)
+