Small issues (and fixes) when moving to Ubuntu 23.04

Recently I upgraded my main Ubuntu system from 22.10 (Kinetic Kudu) to 23.04 (Lunar Lobster). I’m used to having little downtime and only minor issues. The same applies now, except that I had some small issues. Since I can not be the only one, I wanted to share these (YMMV). pipewire Sound worked fine after the update, except for the volume knob of my Das Keyboard 4 (Ultimate Edition). Controlling the volume via the GUI worked fine by the way.