how to update a heroku app code example
Example 1: heroku and github on termi
$ heroku git:remote -a thawing-inlet-61413
set git remote heroku to https://git.heroku.com/thawing-inlet-61413.git
Example 2: how to update heroku
heroku update
#(OR)
sudo apt update && sudo apt install heroku
# to update heroku
Example 3: heroku and github on termi
$ git push heroku master
Initializing repository, done.
updating 'refs/heads/master'
...
Example 4: heroku and github on termi
$ git remote rename heroku heroku-staging