Bump flake8 from 4.0.0 to 4.0.1

Bumps [flake8](https://github.com/pycqa/flake8) from 4.0.0 to 4.0.1.
- [Release notes](https://github.com/pycqa/flake8/releases)
- [Commits](PyCQA/flake8@4.0.0...4.0.1)

---
updated-dependencies:
- dependency-name: flake8
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements-tests.txt

@@ -1,5 +1,5 @@
 -r requirements.txt
 pytest==6.2.5
 pytest-cov==3.0.0
-flake8==4.0.0
+flake8==4.0.1
 pyflakes==2.4.0