Switch to `pkgutil namespace technique <https://packaging.python.org/guides/packaging-namespace-packages/pkgutil-style-namespace-packages>`_ for the ``jaraco`` namespace.
2.0
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* In pmxbot plugin, drop support for legacy config variable. Any applications still using ``google_translate_API_key`` should instead supply that value with ``Google API key``.
* Drop support for Python 3.5 and earlier.
1.3
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Prefer the 'Google API key' config variable for the pmxbot plugin, matching the expectation in pmxbot 1115.2 for the search function.