pip install failed because numpy2.0 release includes breaking changes

[hongjic]

pip install failed because numpy2.0 release includes breaking changes.
all new installs of coremltools should be breaking now.

probably should limit numpy dependency <2.0.0

Stack Trace

coremltools/converters/mil/mil/types/type_mapping.py", line 423, in numpy_type_to_builtin_type
    if np.issubclass_(type(nptype), np.dtype):
..
venv/lib/python3.9/site-packages/numpy/__init__.py", line 397, in __getattr__
    raise AttributeError(
AttributeError: `np.issubclass_` was removed in the NumPy 2.0 release. Use `issubclass` builtin instead.

as an example.

To Reproduce

pip install coremltools in a new environment (which will install numpy2.0). do model conversion and shows the above error

System environment (please complete the following information):

• coremltools version: 8.0b1

[DawerG]

Here is a PR that pins numpy version to be less 2.0 as suggested.