If you made changes to this boilerplate and want to test them, commit your changes and use git archive -o boilerplate.zip HEAD to create the template zip. Then, do a cd .. and a django-admin startproject theprojectname --extension py,yml,json --name Procfile,README.md,.env.example --template=django-react-boilerplate/boilerplate.zip to test the project bootstrap.
Push your changes to a branch and visit https://dashboard.heroku.com/new?template=https://github.com/fill-org-or-user/fill-project-repo-name/tree/fill-branch (replace all fill-*).
Read this.
P.S. if you want to deploy in a different way please check the app.json file for what needs to be configured.
Read this for a more detailed guide on best practices for opening PRs.