Update dependency flake8 to ~=3.9.2

[Jasper-Ben]

This PR contains the following updates:

Package	Update	Change
flake8 (changelog)	minor	~=3.7.7 -> ~=3.9.2

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Release Notes

pycqa/flake8 (flake8)

### [`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) ### [`v3.9.1`](https://togithub.com/pycqa/flake8/compare/3.9.0...3.9.1) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.9.0...3.9.1) ### [`v3.9.0`](https://togithub.com/pycqa/flake8/compare/3.8.4...3.9.0) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.8.4...3.9.0) ### [`v3.8.4`](https://togithub.com/pycqa/flake8/compare/3.8.3...3.8.4) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.8.3...3.8.4) ### [`v3.8.3`](https://togithub.com/pycqa/flake8/compare/3.8.2...3.8.3) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.8.2...3.8.3) ### [`v3.8.2`](https://togithub.com/pycqa/flake8/compare/3.8.1...3.8.2) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.8.1...3.8.2) ### [`v3.8.1`](https://togithub.com/pycqa/flake8/compare/3.8.0...3.8.1) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.8.0...3.8.1) ### [`v3.8.0`](https://togithub.com/pycqa/flake8/compare/3.7.9...3.8.0) [Compare Source](https://togithub.com/pycqa/flake8/compare/3.7.9...3.8.0)

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