cppcoreguidelines-pro-type-union-access

According to https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md using union for type-punning is undefined behaviour.
 Replace it with std::memcpy

src/Base/QuantityPyImp.cpp

@@ -595,8 +595,7 @@ Py::Object QuantityPy::getUnit() const
 
 void QuantityPy::setUnit(Py::Object arg)
 {
-    union PyType_Object pyType = {&(Base::UnitPy::Type)};
-    Py::Type UnitType(pyType.o);
+    Py::Type UnitType(Base::getTypeAsObject(&Base::UnitPy::Type));
     if(!arg.isType(UnitType))
         throw Py::AttributeError("Not yet implemented");