Update dependency flake8 to v4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
flake8 (changelog)	3.9.1 -> 4.0.1

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Release Notes

pycqa/flake8

### [`v4.0.1`](https://togithub.com/pycqa/flake8/compare/4.0.0...4.0.1) [Compare Source](https://togithub.com/pycqa/flake8/compare/4.0.0...4.0.1) ### [`v4.0.0`](https://togithub.com/pycqa/flake8/compare/3.9.2...4.0.0) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.9.2...4.0.0) ### [`v3.9.2`](https://togithub.com/pycqa/flake8/compare/3.9.1...3.9.2) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.9.1...3.9.2)

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Configuration

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[codecov[bot]]

Codecov Report

Merging #103 (166e077) into master (b63978c) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #103   +/-   ##
=======================================
  Coverage   97.45%   97.45%           
=======================================
  Files          29       29           
  Lines         983      983           
=======================================
  Hits          958      958           
  Misses         25       25           

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