Update dependency pyflakes to v2.4.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
pyflakes	==2.3.1 -> ==2.4.0

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Release Notes

PyCQA/pyflakes

### [`v2.4.0`](https://togithub.com/PyCQA/pyflakes/compare/2.3.1...2.4.0) [Compare Source](https://togithub.com/PyCQA/pyflakes/compare/2.3.1...2.4.0)

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