chore(deps-dev): bump flake8 from 3.9.2 to 4.0.1 (#789)

Bumps [flake8](https://github.com/pycqa/flake8) from 3.9.2 to 4.0.1.
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/PyCQA/flake8/commit/82b698e09996cdde5d473e234681d8380810d7a2"><code>82b698e</code></a> Release 4.0.1</li>
<li><a href="https://github.com/PyCQA/flake8/commit/0fac346d8437d205e508643253c7a7d5fdf5dee7"><code>0fac346</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/pycqa/flake8/issues/1410">#1410</a> from PyCQA/parallel-syntax-error</li>
<li><a href="https://github.com/PyCQA/flake8/commit/aa54693c9ec03368c6e592efff4dd4757dd72a47"><code>aa54693</code></a> fix parallel execution collecting a SyntaxError</li>
<li><a href="https://github.com/PyCQA/flake8/commit/d31c5356bbb0a884555662185697ddc6bb46a44c"><code>d31c535</code></a> Release 4.0.0</li>
<li><a href="https://github.com/PyCQA/flake8/commit/afd2399b4cc9b27c4e8a5c2dec8444df8f480293"><code>afd2399</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/pycqa/flake8/issues/1407">#1407</a> from asottile/setup-cfg-fmt</li>
<li><a href="https://github.com/PyCQA/flake8/commit/960cf8cf2044359d5fbd3454a2a9a1d7a0586594"><code>960cf8c</code></a> rerun setup-cfg-fmt (and restore comments)</li>
<li><a href="https://github.com/PyCQA/flake8/commit/d7baba5f14091e7975d2abb3ba9bf321b5be6102"><code>d7baba5</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/pycqa/flake8/issues/1406">#1406</a> from asottile/update-versions</li>
<li><a href="https://github.com/PyCQA/flake8/commit/d79021aafc809d999c4cbbc0a513a5ceb473efa2"><code>d79021a</code></a> update dependency versions</li>
<li><a href="https://github.com/PyCQA/flake8/commit/283f0c81241673221d9628beb11e2d7356826f00"><code>283f0c8</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/pycqa/flake8/issues/1404">#1404</a> from PyCQA/drop-xdg-config</li>
<li><a href="https://github.com/PyCQA/flake8/commit/807904aebc20814ac595b0004ab526fffb5ef681"><code>807904a</code></a> Drop support for Home and XDG config files</li>
<li>Additional commits viewable in <a href="https://github.com/pycqa/flake8/compare/3.9.2...4.0.1">compare view</a></li>
</ul>
</details>
<br />


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</details>

pyproject.toml

@@ -32,7 +32,7 @@ email-validator = {version = "*", optional = true }
 coverage = {extras = ["toml"], version = "^6.1"}
 pytest = "^6.2.5"
 black = "^21.11b1"
-flake8 = "^3.9.0"
+flake8 = "^4.0.1"
 flake8-black = "^0.2.3"
 flake8-builtins = "^1.5.3"
 flake8-comprehensions = "^3.7.0"