np.object deprecation warning

[Ethan-DeBandi99]

Running make test produces the warning shown below. This needs to be updated per the deprecation warning.

tests/import_export_test.py: 24 warnings
  /opt/homebrew/Caskroom/miniforge/base/envs/arkouda/lib/python3.9/site-packages/tables/array.py:241: DeprecationWarning: `np.object` is a deprecated alias for the builtin `object`. To silence this warning, use `object` by itself. Doing this will not modify any behavior and is safe. 
  Deprecated in NumPy 1.20; for more details and guidance: https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
    (oid, self.atom, self.shape, self._v_chunkshape) = self._open_array()