Update pytest-cov requirement from ==2.10.* to ==2.11.* (#113)

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...v2.11.0)

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

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

requirements-test.txt

@@ -1,6 +1,6 @@
 pytest==6.2.*
 pytest-vcr==1.0.*
-pytest-cov==2.10.*
+pytest-cov==2.11.*
 black==20.8b1
 isort==5.7.*
 flake8==3.8.*