Bump flake8 from 5.0.4 to 6.0.0

Bumps [flake8](https://github.com/pycqa/flake8) from 5.0.4 to 6.0.0.
- [Release notes](https://github.com/pycqa/flake8/releases)
- [Commits](PyCQA/flake8@5.0.4...6.0.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

setup.py

@@ -5,7 +5,7 @@
     "tests": ["pytest", "pytz", "simplejson"],
     "lint": [
         "mypy==0.991",
-        "flake8==5.0.4",
+        "flake8==6.0.0",
         "flake8-bugbear==22.10.25",
         "pre-commit~=2.4",
     ],