Python 3.12 Support When Installing via pip

I am posting this here as a known issue that we can point to when people ask.

As mentioned in [this issue](https://github.com/CadQuery/cadquery/issues/1471), our Python 3.12 support is broken right now when isntalling via pip because of our dependency `nlopt`. I expect this package will be fixed for Python 3.12 eventually (just like it was with 3.11), but for now we have to wait.

CadQuery installed via conda ([instructions here](https://cadquery.readthedocs.io/en/latest/installation.html#install-the-conda-package-manager)) seems to work fine with Python 3.12, so that is an option.