Update pytest-cov requirement from <3.1,>=2.10 to >=2.10,<4.1

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@v2.10.0...v4.0.0)

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

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

setup.py

@@ -38,7 +38,7 @@ def read(*parts):
 tests_require = [
     'codecov==2.1.*',
     'coverage>=5.3,<6.5',
-    'pytest-cov>=2.10,<3.1',
+    'pytest-cov>=2.10,<4.1',
     'pytest-env==0.6.*',
     'pytest>=6.1,<7.2',
     'pycodestyle>=2.6,<2.10'