ENH: array API "namespace"

[tylerjereddy]

When running the array API testsuite with pykokkos, one can see this warning: hypothesis/extra/array_api.py:789: HypothesisWarning: Could not determine whether module pykokkos is an Array API library.

If you look at the related code block in hypothesis testing library proper:

    try:
        array = xp.zeros(1)
        array.__array_namespace__()
    except Exception:
        warn(
            f"Could not determine whether module {xp.__name__} is an Array API library",
            HypothesisWarning,
        )   

For details on the requirements for this __array_namespace__() method see:

• https://data-apis.org/array-api/latest/purpose_and_scope.html?highlight=array_namespace#how-to-adopt-this-api
• https://data-apis.org/array-api/latest/API_specification/generated/signatures.array_object.array.__array_namespace__.html#signatures.array_object.array.__array_namespace__

[tylerjereddy]

With the latest version of hypothesis this now causes real testing failure:

ImportError while loading conftest '/home/tyler/github_projects/array-api-tests/conftest.py'.
conftest.py:7: in <module>
    from array_api_tests import _array_module as xp
array_api_tests/__init__.py:44: in <module>
    xps = array_api.make_strategies_namespace(_xp)
../../python_310_pykokkos_work/lib/python3.10/site-packages/hypothesis/extra/array_api.py:895: in make_strategies_namespace
    check_argument(
../../python_310_pykokkos_work/lib/python3.10/site-packages/hypothesis/extra/_array_helpers.py:52: in check_argument
    raise InvalidArgument(fail_message.format(*f_args, **f_kwargs))
E   hypothesis.errors.InvalidArgument: Array module pykokkos has no attribute __array_api_version__, which is required when inferring api_version. If you believe pykokkos is indeed an Array API module, try explicitly passing an api_version.

We may need to pin hypothesis for a little bit until we sort this out..

[tylerjereddy]

Example of failure in CI is here: #98