The official CMake download page still lists that APT repository as one of the alternate distribution avenues. As far as I’m aware, it is still actively maintained, but I’m not involved in that, so one of the Kitware folks would have to provide a more definitive answer on what they officially support.
We’ll likely add Noble (24.04) as it is an LTS. It is still maintained and added to, but the set of versions to build for seems to have stagnated. I’ll see about what the plan going forward is.