Ensure ctkAbstractPythonManagerTest compiles using Qt 4.6.2

See #190

Libs/Scripting/Python/Core/Testing/Cpp/ctkAbstractPythonManagerTest.cpp

@@ -11,6 +11,11 @@
 #include <iostream>
 
 //-----------------------------------------------------------------------------
+#if QT_VERSION < 0x040700
+  Q_DECLARE_METATYPE(QVariant)
+#endif
+
+//-----------------------------------------------------------------------------
 class ctkAbstractPythonManagerTester: public QObject
 {
   Q_OBJECT