Bump flake8 from 5.0.3 to 5.0.4

Bumps [flake8](https://github.com/pycqa/flake8) from 5.0.3 to 5.0.4.
- [Release notes](https://github.com/pycqa/flake8/releases)
- [Commits](PyCQA/flake8@5.0.3...5.0.4)

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

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

Author: dependabot[bot]

requirements.txt

@@ -2,6 +2,6 @@ Django>=2.2
 Wagtail>=2.8
 bandit==1.7.4
 black==22.6.0
-flake8==5.0.3
+flake8==5.0.4
 isort==5.10.1
 pydocstyle==6.1.1