build(deps): update flake8 requirement from >4 to >=7.3.0

Updates the requirements on [flake8](https://github.com/pycqa/flake8) to permit the latest version.
- [Commits](PyCQA/flake8@4.0.1...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]

lint-requirements.txt

@@ -1,6 +1,6 @@
 diff_cover < 10.3
 pydocstyle < 6.4
-flake8 > 4
+flake8 >= 7.3.0
 flake8-bugbear < 25.12
 bandit < 1.9.5
 pylint < 4.1