Fix Cora loading test on Windows (#1705)
Fix Cora loading test on Windows (#1705)

NumPy translates `int` to `np.int_` equivalent to the C `long` type. This type
has different behaviour and size on different platforms, in particular Windows
(LLP64, becomes `np.int32`) vs. Linux/macOS (LP64, becomes `np.int64`):
https://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models

For the test here, the underlying data always ends up as `int64`, so we can just
test that.

See: #1698

stellargraph/stellargraph,stellargraph/stellargraph