property change signal can't be detected when mentioned on C++ side.

Rectangle {
    id: root
    color: "#000000"
    width: 800
    height: 480

    TestModel.onTestPropChanged: console.log("changed")
}

#include <qul/singleton.h>
#include <qul/property.h>

class TestModel : public Qul::Singleton<TestModel>
{
public:
    Qul::Property<int> testProp;
};