Update flake8 requirement from >=4.0.0 to >=5.0.4

Updates the requirements on [flake8](https://github.com/pycqa/flake8) to permit the latest version.
- [Commits](PyCQA/flake8@5.0.4...5.0.4)

---
updated-dependencies:
- dependency-name: flake8
  dependency-version: 5.0.4
  dependency-type: direct:production
...

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

Author: dependabot[bot]

test-requirements.txt

@@ -1,6 +1,6 @@
 pytest >= 8.3.5
 pytest-cov >= 2.8.1
 tox >= 3.9.0
-flake8 >= 4.0.0
+flake8 >= 5.0.4
 types-python-dateutil >= 2.8.19.14
 mypy >= 1.5