build(deps): bump pytest-cov from 5.0.0 to 6.0.0 in /requirements

Bumps [pytest-cov](https://github.com/pytest-dev/pytest-cov) from 5.0.0 to 6.0.0.
- [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
  update-type: version-update:semver-major
...

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

requirements/requirements_test.txt

@@ -1,5 +1,5 @@
 ansys-mapdl-core>=0.60.4
 matplotlib>=3.5.3
 pytest==8.3.3
-pytest-cov==5.0.0
+pytest-cov==6.0.0
 scipy>=1.7.3