Add workaround for warning emitted when junitxml is used. Ref pytest-dev/pytest#6178.

Author: jaraco

pytest.ini

@@ -2,6 +2,8 @@
 norecursedirs=dist build .tox .eggs
 addopts=--doctest-modules --flake8 --black --cov
 doctest_optionflags=ALLOW_UNICODE ELLIPSIS
+# workaround for warning pytest-dev/pytest#6178
+junit_family=xunit2
 filterwarnings=
     # https://github.com/pytest-dev/pytest/issues/6928
     ignore:direct construction of .*Item has been deprecated:DeprecationWarning