Deploy to Heroku button

[FelixStips]

Describe the bug
Deploy to Heroku button uses deprecated Heroku-18 stack.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'https://github.com/papercups-io/papercups'
2. Click on 'Deploy to Heroku'
3. See error

Error:

Your app's stack is approaching end-of-life (Heroku-18)
Your recently built app gefinal-chat is using the Heroku-18 stack, which is deprecated. Since February 1st, 2023, the first build of each Heroku-18 app within a 7-day period has been failing with a deprecation notice. From April 1st, 2023, the frequency of these failures will increase to the first build of each app per day. On April 30th, 2023, Heroku-18 reaches end-of-life; apps using it will no longer receive security updates, and be run at your own risk. From May 1st, 2023, builds will no longer be allowed for Heroku-18 apps. Please upgrade to a newer stack as soon as possible. See the Heroku-18 End-Of-Life FAQ for more details.

[Arena-of-AI]

Hi Felix, I am facing the same problem. Was yours solved? Thanks!

[FelixStips]

Unfortunately not