MAINT: Remove np.int_

[mtsokol]

Hi!
This PR addresses changes that will be shipped in numpy/numpy#24794 - deprecation of np.int_ and np.uint.

Additionally, I see that in the codebase you use np.lib.function_base._parse_gufunc_signature. It's a private function and it will raise an attribute error for NumPy 2.0:

AttributeError: `np.lib.function_base` is now private. If you are using a public function, it should be available in the main numpy namespace, otherwise check the NumPy 2.0 migration guide.

I think there are two options:

1. The call to the private function could be removed from the codebase (e.g. by vendoring implementation - I think it's just a couple lines long).
2. NumPy could potentially make this function part of the public API.

What is your opinion?

[Zac-HD]

Thanks so much for the PR! Fixing this in Numpy and the ecosystem is well above and beyond the call of duty 🤩

To get CI to pass, we'll just need to create hypothesis-python/RELEASE.rst with contents such as:

RELEASE_TYPE: patch

This patch makes some small changes to our NumPy integration to ensure forward compatibility.
Thanks to Mateusz Sokół for :pull:`3761`.

(and I'd be delighted if you added yourself to the AUTHORS.rst too)

As to np.lib.function_base._parse_gufunc_signature, it looks like we only use that in our tests to check that our independent implementation is consistent with NumPy's. Let's just delete that part of the test, the implementation is clearly stable 😁

[mtsokol]

Hi @Zac-HD! The PR is ready from my side.