Composer installs old version of plainkit

I am attempting to install the latest version of the kirby plainkit via composer, however it is only installing version “3.5.8”.

Even when attempting to update via composer with the below line, it does not update to version 3.6.1.

composer update getkirby/cms

Is there something I should check to rectify?

Thanks!

Looks like it was to do with my OS running php 7.3 and not 7.4-8.