Part: modernize C++: return braced init list

src/Mod/Part/App/BRepOffsetAPI_MakePipeShellPyImp.cpp

@@ -68,7 +68,7 @@ int BRepOffsetAPI_MakePipeShellPy::PyInit(PyObject* /*args*/, PyObject* /*kwd*/)
 // returns a string which represents the object e.g. when printed in python
 std::string BRepOffsetAPI_MakePipeShellPy::representation() const
 {
-    return std::string("<BRepOffsetAPI_MakePipeShell object>");
+    return {"<BRepOffsetAPI_MakePipeShell object>"};
 }
 
 PyObject* BRepOffsetAPI_MakePipeShellPy::setFrenetMode(PyObject *args)