Update pyflakes to 2.2.0

[pyup-bot]

This PR updates pyflakes from 2.1.1 to 2.2.0.

Changelog

2.2.0

- Include column information in error messages
- Fix ``overload`` detection with other decorators and in non-global scopes
- Fix return-type annotation being a class member
- Fix assignment to ``_`` in doctests with existing ``_`` name
- Namespace attributes which are attached to ast nodes with ``_pyflakes_`` to
avoid conflicts with other libraries (notably bandit)
- Add check for f-strings without placeholders
- Add check for unused/extra/invalid ``'string literal'.format(...)``
- Add check for unused/extra/invalid ``'string literal % ...``
- Improve python shebang detection
- Allow type ignore to be followed by a code `` type: ignore[attr-defined]``
- Add support for assignment expressions (PEP 572)
- Support ``overload`` detection from ``typing_extensions`` as well
- Fix ``overload`` detection for async functions
- Allow ``continue`` inside ``finally`` in python 3.8+
- Fix handling of annotations in positional-only arguments
- Make pyflakes more resistant to future syntax additions
- Fix false positives in partially quoted type annotations
- Warn about ``is`` comparison to tuples
- Fix ``Checker`` usage with async function subtrees
- Add check for ``if`` of non-empty tuple
- Switch from ``optparse`` to ``argparse``
- Fix false positives in partially quoted type annotations in unusual contexts
- Be more cautious when identifying ``Literal`` type expressions

Links

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

[pyup-bot]

Closing this in favor of #460