Something like this in packit-service.yaml should allow any GitProject from forgejo to utilise the token, but that's not working.
authentication:
github.com:
github_app_id: '123456'
github_app_private_key_path: /secrets/private-key.pem
src.fedoraproject.org:
instance_url: https://src.fedoraproject.org
token: <package_api_key>
forgejo:
instance_url: https://codeberg.org
token: <token>