updated the xunit report to conform to junit 5 xsd

The xunit reporter didn't conform to junit 5 xsd, causing all xunit files to fail validation.

junit 5 xsd:
https://svn.jenkins-ci.org/trunk/hudson/dtkit/dtkit-format/dtkit-junit-model/src/main/resources/com/thalesgroup/dtkit/junit/model/xsd/junit-5.xsd