[IO-603][external] Update to work with current versions of NumPy

[owencjones]

Upolygon was stuck working with only NumPy versions 1.23.5 and below, as it used a dtype=np.int which was deprecated in NumPy 1.24.0

This update updates the dtype to the nearest equivalent which is np.int_ - the alias for the C type long. It's a minor change, and doesn't make any difference to the compiled code, as this will use long anyway, but will avoid raised errors in usage of Upolygon, which are of Fatal type.

Same has been done with np.float to np.floating - but notably here the fused type we use for this encompasses more than these, and not all of them, and we may need a better approach in future?

Reviewers to consider whether a different dtype would suit the python users of Upolygon better, as I've chosen this based on the C type, but we may find that Python int etc are better suited. Won't affect performance as C-type will still be long, as it's defined in a cdef.

@simedw and @andreaazzini comments welcomed especially, as you have greatest exposure to code base, thanks 😄

[Nathanjp91]

LGTM

[simedw]

LGTM