I want to install  OpenProject with DEB/RPM packages on Ubuntu 20.04 and I wonder what database version can be used.

System requirements states "Database: PostgreSQL Version >= 13"

The "openproject configure" dialog contains:

… If you choose to INSTALL, a new PostgreSQL v10 server will be downloaded and installed on your server, …

but the installation does fail because PostgreSQL 10 is not available for my machine.

"apt list -a postgresql" shows version 12 only on Ubuntu 20.04.

I did also install a Univention-server for testing where OpenProject works. On that machine is PostgreSQL  version 9.6 installed.

What database version should be used for a fresh installation?