Error in index/base.py when using NumPy 1.24 or higher - Replace `np.int` with `np.int_`

[KimJongkwang]

I encountered an issue when using mlens that relates to the index/base.py file. Specifically, in line 83, the code sizes = (n // p) * np.ones(p, dtype=np.int) throws an error when using NumPy version 1.24 or higher.

It appears that the use of np.int has been deprecated in NumPy 1.20 and later versions. To resolve this issue, I suggest replacing dtype=np.int with dtype=np.int_. The corrected code should look like this: sizes = (n // p) * np.ones(p, dtype=np.int_).

Please consider making this modification to ensure compatibility with NumPy versions 1.24 and higher.

Thank you.