Gui: modernize C++: return braced init list

src/Gui/PythonWorkbenchPyImp.cpp

@@ -42,7 +42,7 @@ using namespace Gui;
 // returns a string which represent the object e.g. when printed in python
 std::string PythonWorkbenchPy::representation() const
 {
-    return std::string("<Workbench object>");
+    return {"<Workbench object>"};
 }
 
 /** Appends a new menu */