Bump flake8 from 4.0.1 to 5.0.4 (#1107)

Bumps [flake8](https://github.com/pycqa/flake8) from 4.0.1 to 5.0.4.
- [Release notes](https://github.com/pycqa/flake8/releases)
- [Commits](PyCQA/flake8@4.0.1...5.0.4)

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

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

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

Author: dependabot[bot]

requirements_dev_optional.txt

@@ -14,7 +14,7 @@ pymongo==4.2.0
 # optional test requirements
 tox==3.25.1
 coverage
-flake8==4.0.1
+flake8==5.0.4
 pytest-cov==3.0.0
 pytest-doctestplus==0.12.0
 pytest-timeout==2.1.0