The default value of ``junit_family`` option will change to ``xunit2`` in pytest 6.0, given
that this is the version supported by default in modern tools that manipulate this type of file.

In order to smooth the transition, pytest will issue a warning in case the ``--junitxml`` option
is given in the command line but ``junit_family`` is not explicitly configured in ``pytest.ini``.

For more information, `see the docs <https://docs.pytest.org/en/latest/deprecations.html#junit-family-default-value-change-to-xunit2>`__.