Heroku

[LISK819129]

Greetings! Im new to this stuff, but when I tried deploying this to heroku ( exact same stuff)

this error comes up

-----> Determining which buildpack to use for this app
-----> Python app detected
-----> Using Python version specified in runtime.txt
 !     Requested runtime (python-3.6.3) is not available for this stack (heroku-20).
 !     Aborting.  More info: https://devcenter.heroku.com/articles/python-support
 !     Push rejected, failed to compile Python app.
 !     Push failed ```
 
 Can you help me with this? Or Do I have to make changes to any files?

Thanks...