只需使用“Method Not Allowed”错误登录烧瓶中的系统

I am trying do a simple login system with Flask. I found many tutorials tested it and then tried to do something on my own. I'm running my app on Heroku and using a postgresql database. I have some problem but I don't know exactly why? In database there is one user, when I'm puting the login and password and then submiting I'm getting error like this:I am trying do a simple login system with Flask