Possibility to relax Ubuntu 20.04 minor version requirement

[alexkrz]

Hi,

I am wondering whether it is necessary to specifically check for Ubuntu version 20.04.3 LTS.
The currently supported version is Ubuntu 20.04.6 and contains lots of important security updates.
Since the minor version changes should not have a relevant impact on the included packages, I would advocate to allow all Ubuntu 20.04.x versions.

I will create a PR and hope that the PR can be accepted.

Kind regards