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:development
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements_dev.txt

@@ -6,4 +6,4 @@ pylint~=3.3; python_version>="3.9"
 pytest~=7.4; python_version<"3.8"
 pytest~=8.3; python_version>="3.8"
 pytest-cov~=4.1; python_version<"3.8"
-pytest-cov~=5.0; python_version>="3.8"
+pytest-cov~=6.0; python_version>="3.8"