Update pytest-cov requirement from <5 to <6

Updates the requirements on [pytest-cov](https://github.com/pytest-dev/pytest-cov) to permit the latest version.
- [Changelog](https://github.com/pytest-dev/pytest-cov/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-cov@v1.0...v5.0.0)

---
updated-dependencies:
- dependency-name: pytest-cov
  dependency-type: direct:development
...

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

setup.py

@@ -77,7 +77,7 @@
  ],
  'test': [
  'pytest<9',
- 'pytest-cov<5',
+ 'pytest-cov<6',
  ],
  },
  entry_points={