Notebook warnings

[barneydobson]

Please check the rendered version of the notebooks for warnings. There are quite a few warnings in this notebook.

Originally posted by Taher Chegini (@cheginit) in #396 (review)

These look pretty rubbish and should be fixable!

[barneydobson]

and the notebooks are super error prone in tests, so might want to cache results and mock them on the repo (with option to rerun with -m downloads or something)

[barneydobson]

in fact possibly just disable them for microsoft runners as those are the ones that seem to fail (and tests/test_swmmanywhere.py::test_swmmanywhere[True] also fails a lot on the windows runners)