pytest v6 deprecations

new release of pytest makes some deprecation warnings into errors

we were getting one from the pytest-pep8 dependency

since we've set up linting via gh actions it seemed reasonable just to
ditch the dependency

Author: rupa deadwyler

tox.ini

@@ -5,11 +5,10 @@ skip_missing_interpreters = True
 [testenv]
 deps=
      pytest
-     pytest-pep8
      pytest-cov
 
 commands=
-     py.test --ignore=build --pep8 -v --cov=ns1 --cov-report=term tests
+     py.test --ignore=build -v --cov=ns1 --cov-report=term tests
 
 [testenv:py27]
 deps=