Upgrade Bitnami Gitlab CE Version

I have an instance of Bitnami Gitlab CE 8.14.3 running with multiple users and projects.

Bitnami has recently released GitLab CE 9.0.5 and we would like to upgrade to the same. However, while reading on Forums, I came to know that backup of Gitlab can be restored on the same version only. If this is true, then how can we upgrade Bitnami Gitlab stack to 9.0.5 from 8.14.3?

Is there a way that alt least user settings and repositories can be migrated and other settings such as SSL Cert, yml files can be upgraded manually? Please confirm