adapt for numpy 2.0

[vincentsarago]

np.unicode_ has been removed in Numpy 2.0

hug/hug/output_format.py

Lines 145 to 147 in e4a3fa4

	@json_convert(str, numpy.unicode_)
	def numpy_stringable(item):
	return str(item)

   import hug
  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/hug/__init__.py", line 36, in <module>
    from hug import (
  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/hug/output_format.py", line 145, in <module>
    @json_convert(str, numpy.unicode_)
                       ^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.9/x64/lib/python3.11/site-packages/numpy/__init__.py", line 397, in __getattr__
    raise AttributeError(
AttributeError: `np.unicode_` was removed in the NumPy 2.0 release. Use `np.str_` instead.