Steps to deploy on Heroku error

-----> Building on the Heroku-20 stack
-----> Python app detected
 !     Requested runtime (python-3.7.6) 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