tests: Enable "runsuite" test This enables some tests with testcases in - test/xsdtest - test/relaxng/OASIS/spectest.xml - test/relaxng/testsuite.xml The XML Schema Test Suite will also be run it was downloaded, see xstc/Makefile.am. Gitlab CI should be updated to fetch these files. There are 10 expected errors in the XSD test suite. This seems to be the case since at least version 2.9.0 from 2012.