Change quickstart button to install build123d from pypi and not git

[GarryBGoode]

Hi!

I noticed that the quickstart with build123d button of OCP VSCode installs the git version of build123d, which is by default the dev branch.

While currently it might be more stable than the pypi release due to a recent issue with cadquery-ocp (see gumyr/build123d#866), I think in the long term it would be better to use the pypi version of build123d for such a quickstart command.

At the moment the correct way to install build123d via pip is pip install build123d "cadquery-ocp<7.8".

[bernhard-42]

Will do as soon as build123d install is stable.
Feel free to change the commands yourself in the configuration of OCP VS Code