cubicweb #17262151 fix qunit tests in devtools [in-progress]

https://jenkins.logilab.org/job/cubicweb-default/465/TOXENV=py3-misc,distributions=cubicweb/testReport/cubicweb.devtools.test.unittest_qunit/QUnitTestCaseTC/test_simple_failure/ says that xauth is missing.

Add it to the dev requirements.

priorityimportant
typebug
done in3.28.0
closed by<not specified>