Fix deprecation warning from np v1.20

[lucasb-eyer]

See also https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations for more info. This does not change semantics.

[lucasb-eyer]

@tylin mind merging this? It can't possibly break anything, but the warnings are just annoying.

[psyhtest]

Starting from NumPy 1.24.0, it's not a warning but an error. Similarly, for other data types:

$ python3
Python 3.8.10 (default, Nov 14 2022, 12:59:47)
[GCC 9.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy as np
>>> np.__version__
'1.24.0'
>>> np.float
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/anton/.local/lib/python3.8/site-packages/numpy/__init__.py", line 284, in __getattr__
    raise AttributeError("module {!r} has no attribute "
AttributeError: module 'numpy' has no attribute 'float'
>>> np.object
<stdin>:1: FutureWarning: In the future `np.object` will be defined as the corresponding NumPy scalar.  (This may have returned Python scalars in past versions.
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/anton/.local/lib/python3.8/site-packages/numpy/__init__.py", line 284, in __getattr__
    raise AttributeError("module {!r} has no attribute "
AttributeError: module 'numpy' has no attribute 'object'
>>> np.bool
<stdin>:1: FutureWarning: In the future `np.bool` will be defined as the corresponding NumPy scalar.  (This may have returned Python scalars in past versions.
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/anton/.local/lib/python3.8/site-packages/numpy/__init__.py", line 284, in __getattr__
    raise AttributeError("module {!r} has no attribute "
AttributeError: module 'numpy' has no attribute 'bool'