Update flake8 requirement from >=3.8.3 to >=7.3.0

Updates the requirements on [flake8](https://github.com/pycqa/flake8) to permit the latest version.
- [Commits](PyCQA/flake8@3.8.3...7.3.0)

---
updated-dependencies:
- dependency-name: flake8
  dependency-version: 7.3.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements/pkgutils.txt

@@ -1,6 +1,6 @@
 setuptools>=40.8.0
 wheel>=0.46.3
-flake8>=3.8.3
+flake8>=7.3.0
 tox>=4.30.3
 sphinx2rst>=1.0
 bumpversion