Fix numpy deprecation warnings

[TimoRoth]

Same as with OGGM, it might be worth to review if some of those np.int should be replace with int32/64 instead.

[TimoRoth]

I don't know why that one test is failing. My understanding is, that np.float/np.int are just aliases for float and int, so changing it should not have ANY side effects.
I tried changing it to np.float_ and np.int_ instead, but that produces a whole lot of other failures.

Edit: Looks like the reason is the -rc test environment pulling in a really old version of Pandas.
The -rc one pulls pandas-1.0.0rc0, while the non-rc gets pandas-1.2.2. A bit weird, given that the goal of it probably is to test more recent versions.

[fmaussion]

Thanks a lot!!! That's awesome