Ooh. I see, I have to update the documentation.
With 25.04 there is no python tab in Setting → Configure Kdenlive → Environment anymore.
After Python is installed you can go direct to Settings → Configure Kdenlive → Plugins and click on install missing dependencies under VOSK and under Whisper as described here: Plugins — Kdenlive Manual 25.08 documentation.
Then all needed packages get installed. VOSK need a bit a special way to install the models, but it’s described how to do it.