This is a buildpack for the Github CLI. The code is taken from the heroku/salesforce-cli-buildpack..
The Github CLI comes with the following plugins :
- gh annotations
The path is already exported in the Heroku .profil.d :
export PATH="$BUILD_DIR/vendor/github/cli/bin:$PATH"
The $BUILD_DIR is the path where your apps source is stored on the Heroku dyno.