Can't push application.yml keys to heroku

[CoconutTherapy]

Hello, I'm trying to push my application.yml keys to heroku with the command figaro heroku:set -e production but I'm getting the following error:

!    Please specify a version along with Heroku's API MIME type. For example, `Accept: application/vnd.heroku+json; version=3`.

I'm on Ubuntu 16.04, I've tried to reinstall heroku as a standalone and through npm, still getting the same error.

halp!