Update importlib_metadata to 3.3.0

[pyup-bot]

This PR updates importlib_metadata from 3.1.1 to 3.3.0.

Changelog

3.3.0

======

* * 265: ``EntryPoint`` objects now expose a ``.dist`` object
referencing the ``Distribution`` when constructed from a
Distribution.

3.2.0

======

* The object returned by ``metadata()`` now has a
formally-defined protocol called ``PackageMetadata``
with declared support for the ``.get_all()`` method.
Fixes 126.

Links

• PyPI: https://pypi.org/project/importlib-metadata
• Changelog: https://pyup.io/changelogs/importlib-metadata/
• Repo: https://github.com/python/importlib_metadata

[duckinator]

bors r+

[bors]

Build succeeded:

• macOS PYTHON:3.6.8
• FreeBSD PYTHON:3.7
• macOS PYTHON:3.7.2
• Zipapp_bootstrap container:python:3.7-slim
• Linux container:python:3.6-slim
• Zipapp_bootstrap container:python:3.8-slim
• FreeBSD PYTHON:3.6
• Lint
• Linux container:python:3.8-slim
• Linux container:python:3.7-slim