在Heroku上部署Flask应用程序时出错＃34;请求的运行时不适用于此堆栈＆＃34;

Question

我试图在Heroku上部署应用程序。我已经包含了runtime.txt文件并包含了最新的python版本3.6.3，但是我收到了以下错误。

    -----> Python app detected
 !     The latest version of Python 3 is python-3.6.3 (you are using python 3.6.3, which is unsupported).
 !     We recommend upgrading by specifying the latest version (python-3.6.3).
       Learn More: https://devcenter.heroku.com/articles/python-runtimes


-----> Installing python 3.6.3
 !     Requested runtime (python 3.6.3) is not available for this stack (heroku-16).
 !     Aborting.  More info: https://devcenter.heroku.com/articles/python-support
 !     Push rejected, failed to compile Python app.
 !     Push failed