Flake8-isort

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- Fix broken `add_options` method [casperdcl]

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- Improve the config option is added and read back. [gforcada]

- Bump plugin version. [gforcada]

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- Update dependencies. [gforcada]

- Revamp GitHub actions. [gforcada]

- Drop python 3.6, and add python 3.10. [gforcada]

- Use linters and formatters to keep code sane and beautiful. [gforcada]

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- Fix compatibility with flake8 version 5. [nhymxu]

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- Release it as a wheel as well. [gforcada]

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- The package no longer depends on ``testfixtures``.