numpy.datetime64[ns] support

[maben-mw]

I am trying to work with numpy.datetime64[ns], but the following:

import numpy
from inference_schema.parameter_types.numpy_parameter_type import NumpyParameterType
from inference_schema.schema_decorators import input_schema

data = numpy.array(["2023-06-06"],'datetime64[ns]')
schema = NumpyParameterType(data)

@input_schema("foo",schema)
def foo():
    pass

Throws:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/tmp/testenv/lib/python3.10/site-packages/inference_schema/schema_decorators.py", line 41, in input_schema
    swagger_schema = {param_name: param_type.input_to_swagger()}
  File "/tmp/testenv/lib/python3.10/site-packages/inference_schema/parameter_types/numpy_parameter_type.py", line 99, in input_to_swagger
    swagger_schema['example'] = self._get_swagger_sample(self.sample_input, items_count, swagger_schema['items'])
  File "/tmp/testenv/lib/python3.10/site-packages/inference_schema/parameter_types/abstract_parameter_type.py", line 88, in _get_swagger_sample
    item_sample = cls._get_data_record_swagger_sample(
  File "/tmp/testenv/lib/python3.10/site-packages/inference_schema/parameter_types/abstract_parameter_type.py", line 127, in _get_data_record_swagger_sample
    sample_swag = cls._timestamp_item_to_string(data_item)
  File "/tmp/testenv/lib/python3.10/site-packages/inference_schema/parameter_types/abstract_parameter_type.py", line 76, in _timestamp_item_to_string
    return cls._datetime_item_to_string(date_item)
  File "/tmp/testenv/lib/python3.10/site-packages/inference_schema/parameter_types/abstract_parameter_type.py", line 82, in _datetime_item_to_string
    return date_item.astype(dt.datetime).strftime("%Y-%m-%d %H:%M:%S,%f")
AttributeError: 'int' object has no attribute 'strftime'

Interestingly datetime64[us] does appear to work fine, but datetime64[ns] does not.