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] <support@github.com>

setup.cfg

@@ -39,7 +39,7 @@ console_scripts =
 [options.extras_require]
 dev =
     pytest<9
-    pytest-cov<5
+    pytest-cov<6
     pytest-xdist<4
 
 [isort]