Bump pytest-cov from 2.12.0 to 2.12.1

Bumps [pytest-cov](https://github.com/pytest-dev/pytest-cov) from 2.12.0 to 2.12.1.
- [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...v2.12.1)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -6,7 +6,7 @@ marshmallow>=3.0,<4.0
 # Test requirements
 pytest
 pytest-django==3.8.0
-pytest-cov==2.12.0
+pytest-cov==2.12.1
 flake8==3.9.2
 
 # MkDocs for documentation