Bump attrs from 21.3.0 to 21.4.0

Created by: dependabot[bot]

Bumps attrs from 21.3.0 to 21.4.0.

Release notes

Sourced from attrs's releases.

21.4.0

This is a quick bug fix release for a regression that causes coverage report fail under certain circumstances.

Full Changelog

Changes

• Fixed the test suite on PyPy3.8 where cloudpickle does not work. #892
• Fixed coverage report for projects that use attrs and don't set a --source. #895, #896

Changelog

Sourced from attrs's changelog.

21.4.0 (2021-12-29)

Changes ^^^^^^^

• Fixed the test suite on PyPy3.8 where cloudpickle does not work. [#892](https://github.com/python-attrs/attrs/issues/892) <https://github.com/python-attrs/attrs/issues/892>_
• Fixed coverage report for projects that use attrs and don't set a --source. [#895](https://github.com/python-attrs/attrs/issues/895) <https://github.com/python-attrs/attrs/issues/895>, [#896](https://github.com/python-attrs/attrs/issues/896) <https://github.com/python-attrs/attrs/issues/896>

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Commits

• 2de9014 Prepare 21.4.0
• 02ba249 Remove dead anchors
• 1ff3f1e Minor changelog polish
• 0575d51 Make virtual repr file names unique (#896)
• 03dd713 Do not require cloudpickle for PyPy (#892)
• ce50f40 Use correct words
• 9424a93 Tell coverage about import attrs
• c86fbc8 Use better word
• 7695908 docs: fix very minor typo (#894)
• ada66be docs: remove typo in README.rst (#893)
• Additional commits viewable in compare view

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