The numpy.ndarray.itemset method was removed from NumPy 2.0

[robrohan]

This just changes a few itemset calls to array index setting calls. The old itemset calls fails on newer numpy versions.

Environment

% python --version => Python 3.11.11

>>> import numpy
>>> numpy.version.version
'2.2.5'

Fixing Issue

% python -m mathematics_dataset.generate --filter=linear_1d

Traceback (most recent call last):
 ...
  File "/Users/robrohan/Projects/SideProjects/mathematics_dataset/mathematics_dataset/sample/polynomials.py", line 222, in sample_coefficients
    coeffs.itemset(index, value)
    ^^^^^^^^^^^^^^
AttributeError: `itemset` was removed from the ndarray class in NumPy 2.0. Use `arr[index] = value` instead.

After the change it generates correctly.