Task: Replace deprecated `pkg_resources`

[mfulgo]

Just opening an issue in case someone else gets around to it before I have a chance:

.../python3.11/site-packages/iso18245/__init__.py:5: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
    from pkg_resources import resource_filename

From that page:

Use of pkg_resources is deprecated in favor of importlib.resources, importlib.metadata and their backports (importlib_resources, importlib_metadata). ...

[jleclanche]

Thanks! If you submit a PR I will merge it.