Update flake8 requirement in the all-dependencies group

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

Updates `flake8` to 7.1.0
- [Commits](PyCQA/flake8@7.0.0...7.1.0)

---
updated-dependencies:
- dependency-name: flake8
  dependency-type: direct:production
  dependency-group: all-dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements-test.txt

@@ -2,7 +2,7 @@
 codecov~=2.1
 cov-core~=1.15
 coverage~=7.5
-flake8~=7.0
+flake8~=7.1
 mock~=5.1
 pytest~=8.2
 pytest-cov~=5.0