Bump pytest-cov from 2.10.1 to 2.11.1

Bumps [pytest-cov](https://github.com/pytest-dev/pytest-cov) from 2.10.1 to 2.11.1.
- [Release notes](https://github.com/pytest-dev/pytest-cov/releases)
- [Changelog](https://github.com/pytest-dev/pytest-cov/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest-cov/compare/v2.10.1...v2.11.1)

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

requirements-dev.txt

@@ -2,7 +2,7 @@
 flake8==3.8.4
 async-timeout==3.0.1
 pytest==6.2.1
-pytest-cov==2.10.1
+pytest-cov==2.11.1
 pytest-mock==3.4.0
 coverage==5.3.1
 sphinx==3.4.1