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

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] <[email protected]>

requirements/requirements-dev.txt

@@ -2,7 +2,7 @@
 vcrpy==6.0.*
 pytest==8.3.*
 pytest-recording==0.13.*
-pytest-cov==5.0.*
+pytest-cov==6.0.*
 pytest-env==1.1.*
 pytest-html==4.1.*
 flake8==7.1.*