Replace np.float with np.float64.

[m43]

Describe your changes

Replacing np.float with np.float64 to support numpy>=1.24.0. The np.float,
np.int, etc. aliases were deprecated in NumPy 1.20 (see the deprecation note),
and deprecation has expired with NumPy 1.24 (Nov 24, 2022).

Using the current Pyhon API with newer Numpy versions will therefore raise the
following error:

Traceback (most recent call last):
  ...
  File ".../lib/python3.8/site-packages/pycocotools/ytvoseval.py", line 407, in accumulate
    tp_sum = np.cumsum(tps, axis=1).astype(dtype=np.float)
  File ".../lib/python3.8/site-packages/numpy/__init__.py", line 305, in __getattr__
    raise AttributeError(__former_attrs__[attr])
AttributeError: module 'numpy' has no attribute 'float'.
`np.float` was a deprecated alias for the builtin `float`. To avoid this error in existing code, use `float` by itself. Doing this will not modify any behavior and is safe. If you specifically wanted the numpy
scalar type, use `np.float64` here.
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

Checklist before requesting a review

• I have performed a self-review of my code

Tests

Works on my machine