Update pytest-cov requirement from ==5.0.* to ==6.0.*

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@v5.0.0...v6.0.0)

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

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

tests/requirements.txt

@@ -1,4 +1,4 @@
 pytest ==8.3.*
-pytest-cov ==5.0.*
+pytest-cov ==6.0.*
 
 twine ==5.1.*