Cleanup pytest warnings

[ymilki]

Problem

tox -e py38 produces some noisy warnings:

PytestDeprecationWarning: @pytest.yield_fixture is deprecated.
  Use @pytest.fixture instead; they are the same.

DeprecationWarning: The SafeConfigParser class has been renamed to ConfigParser in Python 3.2. This alias will be removed in future versions. Use ConfigParser directly instead.

Unknown pytest.mark.acceptance - is this a typo?  You can register custom marks to avoid this warning - for details, see https://docs.pytest.org/en/stable/how-to/mark.html

Solution

Implement warning advice

Action Plan

• Merge before Update version to 0.11.1 #116

[dnephin]

Thanks!