Fix initiating duration arrays with numpy array

[anuragm]

Numpy does not supports using a non-empty array as a truth value, causing the following example to fail:

import numpy as np
import oqpy

npduration = oqpy.ArrayVar(
    name="npinit",
    init_expression=np.arange(11) * 1e-9,
    dimensions=[11],
    base_type=oqpy.DurationVar,
)

with stack trace

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[3], line 4
      1 import numpy as np
      2 import oqpy
----> 4 npduration = oqpy.ArrayVar(
      5     name="npinit",
      6     init_expression=np.arange(11) * 1e-9,
      7     dimensions=[11],
      8     base_type=oqpy.DurationVar,
      9 )

File ~/Work/oqpy/oqpy/classical_types.py:377, in ArrayVar.__init__(self, dimensions, base_type, *args, **kwargs)
    374     array_base_type = base_type_instance.type_cls()
    376 # Automatically handle Duration array.
--> 377 if base_type is DurationVar and kwargs["init_expression"]:
    378     kwargs["init_expression"] = (make_duration(i) for i in kwargs["init_expression"])
    380 super().__init__(
    381     *args,
    382     **kwargs,
    383     dimensions=[ast.IntegerLiteral(dimension) for dimension in dimensions],
    384     base_type=array_base_type,
    385 )

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

Changing the comparison condition fixes this issue.

[jcjaskula-aws]

LGTM, thanks