In this case, check the release notes packages (release-notes-uyuni for the
server, release-notes-uyuni-proxy for the proxy), and of course the WebUI.

With 4.0.X we didn't change the version of the pattern package.

With 2020.XX we are changing it, so pattern for 2020.04 will be version
2020.04.

This is, assuming you are using Stable.

If you are using devel/master, there's no versioning as such there. We adjust
versions usually during promotion to Stable.