Move coverage dependency to setup and remove pytest-cov,

as not being used currently

setup.py

@@ -74,7 +74,7 @@ setup(
     ],
     extras_require={
         'dev': ['flake8'],
-        'test': ['tox', 'pytest', 'pytest-cov'],
+        'test': ['tox', 'pytest', 'coverage'],
         # recommonmark: to make sphinx render markdown
         'doc': ['sphinx', 'recommonmark'],
     },

tox.ini

@@ -20,7 +20,7 @@ commands =
 skip_install = True
 changedir={toxinidir}
 deps =
-   coverage
+   .[test]
 commands=
    # nothing to combine while not using several python versions
    # coverage combine