Bump flake8 from 5.0.4 to 6.1.0 in /requirements/CI

Bumps [flake8](https://github.com/pycqa/flake8) from 5.0.4 to 6.1.0.
- [Commits](PyCQA/flake8@5.0.4...6.1.0)

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

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

requirements/CI/requirements.txt

@@ -1,5 +1,5 @@
 coverage==6.3.3
-flake8==5.0.4
+flake8==6.1.0
 pytest==7.2.1
 pytest-cov==4.0.0
 pytest-xdist==3.2.0