Windows broken for nb-tester due to pyscf

[Eric-Arellano]

#2148 added pyscf as a dependency, although it's only used in docs/guides/qiskit-addons-sqd-get-started.ipynb.

This breaks Windows users because https://pypi.org/project/pyscf/#files doesn't support Windows. So, Windows users can't run tox for our nb-tester program.

We should use an env marker like tweedledum; platform_system != "Darwin" to not install pyscf on Windows. We should also consider somehow indicating with nb-tester config that the notebook doesn't work on Windows so that you can still use tox to execute all notebooks.

Update Jan 23, 2025: We should go for the quick fix to use an env marker like ; platform_system != "Darwin" (but Windows). It's acceptable that tox won't work for every notebook; we don't need to know to skip that notebook on Windows.