I can’t help you with bitnami, I use official Gitlab packages. But if the upgrade had been done then the version should have shown correctly. You could reboot the server to make sure and then check version information again. If not, then that would suggest the upgrade didn’t work. Not sure if bitnami is different to the official packages from Gitlab or not. Either way, you would need to post a lot more information, best would be copy the entire text from the console when doing the upgrade so that we can see what is going on.
Bitnami has documentation for administrative tasks, including upgrades. Unfortunately I have no idea which Linux distribution is used for Bitnami VMs. Suggest SSH’ing into the box and running cat /etc/os-release to figure out whether the package manager is apt (Debian/Ubuntu), yum (CentOS/RHEL), zypper (SuSE), etc. Then follow Upgrading from 13.12 to Latest - #2 by iwalker