Update packaging to 21.2

[pyup-bot]

This PR updates packaging from 20.9 to 21.2.

Changelog

21.2

~~~~~~~~~~~~~~~~~

* Update documentation entry for 21.1.

21.1

~~~~~~~~~~~~~~~~~

* Update pin to pyparsing to exclude 3.0.0.

21.0

~~~~~~~~~~~~~~~~~

* PEP 656: musllinux support (:issue:`411`)
* Drop support for Python 2.7, Python 3.4 and Python 3.5.
* Replace distutils usage with sysconfig (:issue:`396`)
* Add support for zip files in ``parse_sdist_filename`` (:issue:`429`)
* Use cached ``_hash`` attribute to short-circuit tag equality comparisons (:issue:`417`)
* Specify the default value for the ``specifier`` argument to ``SpecifierSet`` (:issue:`437`)
* Proper keyword-only "warn" argument in packaging.tags (:issue:`403`)
* Correctly remove prerelease suffixes from ~= check (:issue:`366`)
* Fix type hints for ``Version.post`` and ``Version.dev`` (:issue:`393`)
* Use typing alias ``UnparsedVersion`` (:issue:`398`)
* Improve type inference for ``packaging.specifiers.filter()`` (:issue:`430`)
* Tighten the return type of ``canonicalize_version()`` (:issue:`402`)

Links

• PyPI: https://pypi.org/project/packaging
• Changelog: https://pyup.io/changelogs/packaging/
• Repo: https://github.com/pypa/packaging

[pyup-bot]

Closing this in favor of #2038