ci for qt 5.5 fails
see:
https://www.graphics.rwth-aachen.de:9000/OpenFlipper-Free/OpenFlipper-Free/-/jobs/31866/raw
ci for qt 5.5 builds fails, or to be more precise ctests fail. the debug output shows, an issue with the used libs. i think the libs that are used fo compilation and the ones that are used when running ctest may not be the same.