Update "Getting Started with Grow"

I’m guessing you hit an issue similar to this.

St7789 install error with Bookworm? - Support - Pimoroni Buccaneers

Installing the Weather HAT Python library fails - Support - Pimoroni Buccaneers

I reverted to Legacy on my Pi 400 so the installers would “just work”, without having to resort to the “new” virtual environment install procedures.