Install Heroku cli in Gitpod to run on startup

Question

I am trying to set up my workspace so the Heroku cli automatically installs on startup. I found directions online but nothing is working and I still have to manually install it every time.

This is what I found: https://community.gitpod.io/t/install-heroku-cli-in-githpod/627/2

.gitpod.yml file

image:
file: .gitpod.Dockerfile

.gitpod.Dockerfile

image:
  file: .gitpod.Dockerfile

# List the start up tasks. Learn more https://www.gitpod.io/docs/config-start-tasks/
tasks:
  - init: echo 'init script' # runs during prebuild
    command: echo 'start script'

# List the ports to expose. Learn more https://www.gitpod.io/docs/config-ports/
ports:
  - port: 3000
    onOpen: open-preview