Bump pytest-cov from 3.0.0 to 4.0.0 (#628)

Bumps [pytest-cov](https://github.com/pytest-dev/pytest-cov) from 3.0.0 to 4.0.0.
- [Release notes](https://github.com/pytest-dev/pytest-cov/releases)
- [Changelog](https://github.com/pytest-dev/pytest-cov/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-cov@v3.0.0...v4.0.0)

---
updated-dependencies:
- dependency-name: pytest-cov
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements/tests.txt

@@ -1,5 +1,5 @@
 coveralls[yaml]==3.3.1
 pytest==7.1.3
-pytest-cov==3.0.0
+pytest-cov==4.0.0
 pytest-mock==3.8.2
 wptserve==3.0