Update flake8 requirement from <7,>=4 to >=4,<8

Updates the requirements on [flake8](https://github.com/pycqa/flake8) to permit the latest version.
- [Commits](PyCQA/flake8@4.0.0...7.0.0)

---
updated-dependencies:
- dependency-name: flake8
  dependency-type: direct:development
...

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

setup.py

@@ -74,7 +74,7 @@ def read(path):
               'createcoverage>=1,<2',
               'dask',
               'stopit>=1.1.2,<2',
-              'flake8>=4,<7',
+              'flake8>=4,<8',
               'pandas<2.1',
               'pytz',
               ],