Update pytest-cov from 2.11.1 to 2.12.0

Author: pyup-bot

requirements/requirements-testing.txt

@@ -2,7 +2,7 @@ django-debug-toolbar==3.2.1
 factory-boy==3.2.0
 Faker==8.1.4
 pytest==6.2.4
-pytest-cov==2.11.1
+pytest-cov==2.12.0
 pytest-django==4.2.0
 pytest-factoryboy==2.1.0
 snapshottest==0.6.0