Update for latest ndarray lib

[dancergraham]

the trait From<pyo3::Bound<'_, PyArray<f64, numpy::ndarray::Dim<[usize; 2]>>>> is not implemented for pyo3::Py<PyArray<f64, ndarray::Dim<[usize; 2]>>>

[dancergraham]

I get the same error on Windows with ndarray=0.16.1 and on ci with PR #32