Bump flake8 from 3.9.2 to 4.0.1 (#95)

Bumps [flake8](https://github.com/pycqa/flake8) from 3.9.2 to 4.0.1.
- [Release notes](https://github.com/pycqa/flake8/releases)
- [Commits](PyCQA/flake8@3.9.2...4.0.1)

---
updated-dependencies:
- dependency-name: flake8
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

setup.py

@@ -27,7 +27,7 @@ def readme():
     packages=["docstr_coverage"],
     install_requires=["click", "PyYAML"],
     extras_require={
-        "lint": ["flake8==3.9.2", "black==22.3.0", "isort==5.9.0"],
+        "lint": ["flake8==4.0.1", "black==22.3.0", "isort==5.9.0"],
         "test": ["pytest==6.2.5", "pytest-mock==3.4.0"],
     },
     include_package_data=True,