Update pytest-cov requirement from <4.0,>=2.12 to >=2.12,<5.0

Updates the requirements on [pytest-cov](https://github.com/pytest-dev/pytest-cov) to permit the latest version.
- [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@v2.12.0...v4.0.0)

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

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

pyproject.toml

@@ -101,7 +101,7 @@ license = { text = "BSD 3-Clause License" }
 [project.optional-dependencies]
 test = [
   "pytest>=6.2.4,<7.2.0",
-  "pytest-cov>=2.12,<4.0",
+  "pytest-cov>=2.12,<5.0",
   "pytest-xdist",
   "pyyaml>=6,<7",
   "recommonmark",