Numpy 2.0 incompatibility

[Holmgren825]

Edu notebooks run on binder are currently not working due to a change in numpy 2.0: np.NaN was removed in the NumPy 2.0 release. Use np.nan instead. This is thrown in the flowline model, so needs to be fixed in OGGM, but this is a larger change. An easy fix here would be to pin numpy < 2.0.

[fmaussion]

I'm amazed the notebooks run on Binder at all. How about classroom?

[Holmgren825]

No problem regarding this specific issue on 1.6.1. There is some bokeh related issue on 1.6.2.

[fmaussion]

1.6.2 we should fix.

Numpy 2.0 support will need more time, probably until end of year (cc @pat-schmitt in case he is not listening here)