1.3.2: pytest warning about use deprecated pkg_resources #393

===================================================================================== warnings summary ======================================================================================
test/ext/test_linguaplugin.py::MakoExtractTest::test_extract
  /usr/lib/python3.9/site-packages/lingua/extractors/__init__.py:1: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
    from pkg_resources import DistributionNotFound

test/ext/test_linguaplugin.py::MakoExtractTest::test_extract
  /usr/lib/python3.9/site-packages/pkg_resources/__init__.py:2846: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('sphinxcontrib')`.
  Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
    declare_namespace(pkg)

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html