use of numpy.int causes an error with newer versions of numpy

[mgalardini]

The following import causes an AttributeError:

from epistasis.models import EpistasisLinearRegression

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Cell In[84], line 2
      1 from gpmap import GenotypePhenotypeMap
----> 2 from epistasis.models import EpistasisLinearRegression

File [~/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/models/__init__.py:6](http://localhost:8888/home/marco/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/models/__init__.py#line=5)
      1 """
      2 A library of models to decompose high-order epistasis in genotype-phenotype
      3 maps.
      4 """
      5 # Import linear models
----> 6 from .linear import (EpistasisLinearRegression,
      7                      EpistasisLasso,
      8                      EpistasisRidge,
      9                      EpistasisElasticNet)
     11 # Import nonlinear models
     12 from .nonlinear import (EpistasisNonlinearRegression,
     13                         EpistasisPowerTransform,
     14                         EpistasisSpline)

File [~/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/models/linear/__init__.py:1](http://localhost:8888/home/marco/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/models/linear/__init__.py#line=0)
----> 1 from .ordinary import EpistasisLinearRegression
      2 from .lasso import EpistasisLasso
      3 from .ridge import EpistasisRidge

File [~/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/models/linear/ordinary.py:4](http://localhost:8888/home/marco/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/models/linear/ordinary.py#line=3)
      1 import numpy as np
      2 from sklearn.linear_model import LinearRegression
----> 4 from ..base import BaseModel, use_sklearn
      5 from ..utils import arghandler
      7 # Suppress an annoying error from scikit-learn

File [~/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/models/base.py:14](http://localhost:8888/home/marco/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/models/base.py#line=13)
     12 # Local imports
     13 from epistasis.mapping import EpistasisMap, encoding_to_sites
---> 14 from epistasis.matrix import get_model_matrix
     15 from epistasis.utils import (extract_mutations_from_genotypes,
     16                              genotypes_to_X)
     17 from .utils import XMatrixException

File [~/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/matrix.py:6](http://localhost:8888/home/marco/miniconda3/envs/epistasis/lib/python3.10/site-packages/epistasis/matrix.py#line=5)
      4 # Try importing model matrix builder from cython extension for speed up.
      5 try:
----> 6     from .matrix_cython import build_model_matrix
      8 except ImportError:
     10     import warnings as _warnings

File matrix_cython.pyx:3, in init epistasis.matrix_cython()

File [~/.local/lib/python3.10/site-packages/numpy/__init__.py:324](http://localhost:8888/home/marco/.local/lib/python3.10/site-packages/numpy/__init__.py#line=323), in __getattr__(attr)
    319     warnings.warn(
    320         f"In the future `np.{attr}` will be defined as the "
    321         "corresponding NumPy scalar.", FutureWarning, stacklevel=2)
    323 if attr in __former_attrs__:
--> 324     raise AttributeError(__former_attrs__[attr])
    326 if attr == 'testing':
    327     import numpy.testing as testing

AttributeError: module 'numpy' has no attribute 'int'.
`np.int` was a deprecated alias for the builtin `int`. To avoid this error in existing code, use `int` by itself. Doing this will not modify any behavior and is safe. When replacing `np.int`, you may wish to use e.g. `np.int64` or `np.int32` to specify the precision. If you wish to review your current use, check the release note link for additional information.
The aliases was originally deprecated in NumPy 1.20; for more details and guidance see the original release note at:
    https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations

I would assume that the cython module needs to be modified to pick a specific int type. I tried the command in a conda environment with numpy version < 1.20 and it worked fine.