Make sure you have Python 3.7 installed locally. To push to Heroku, you'll need to install the Heroku CLI, as well as Postgres.
$ git clone https://github.com/cnvoice/cnvoice.git
$ cd cnvoice
$ python3 -m venv cnvoice
$ pip install -r requirements.txt
$ heroku local
Your app should now be running on localhost:5000.
$ heroku create
$ git push heroku master
$ heroku open
For more information about using Python on Heroku, see these Dev Center articles: