Set junit_family to xunit2 in pytest.ini
Set junit_family to xunit2 in pytest.ini

This avoids a warning like:

Warning: The 'junit_family' default value will change to 'xunit2' in pytest 6.0.
  Add 'junit_family=xunit1' to your pytest.ini file to keep the current format in future versions of pytest and silence this warning.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@openrobotics.org>

ros2/launch,ros2/launch,ros2/launch