chore(deps): 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@v5.0.0...v6.0.0)

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

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

requirements-testing.txt

@@ -2,7 +2,7 @@ coverage[toml] ~= 7.6; python_version == '3.7'
 coverage[toml] == 7.*; python_version > '3.7'
 coverage-conditional-plugin == 0.9.*
 pytest == 7.*
-pytest-cov == 5.*
+pytest-cov == 6.*
 pytest-timeout == 2.*
 pytest-xdist == 3.*
 freezegun == 1.*