Sheet: modernize C++: return braced init list

src/Mod/Spreadsheet/Gui/ViewProviderSpreadsheetPyImp.cpp

@@ -32,7 +32,7 @@ using namespace SpreadsheetGui;
 // returns a string which represents the object e.g. when printed in python
 std::string ViewProviderSpreadsheetPy::representation() const
 {
-    return std::string("<ViewProviderSpreadsheet object>");
+    return {"<ViewProviderSpreadsheet object>"};
 }
 
 PyObject* ViewProviderSpreadsheetPy::getView(PyObject* args)