Update pytest-cov requirement from <4.0.0,>=2.12.0 to >=2.12.0,<5.0.0

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] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -66,7 +66,7 @@ Source = "https://github.com/eadwinCode/ellar"
 [project.optional-dependencies]
 test = [
     "pytest >=6.2.4,<8.0.0",
-    "pytest-cov >=2.12.0,<4.0.0",
+    "pytest-cov >=2.12.0,<5.0.0",
     "mypy ==0.971",
     "flake8 >=3.8.3,<4.0.0",
     "black ==22.8.0",