Fem: modernize C++: use equals default

src/Mod/Fem/Gui/AppFemGuiPy.cpp

@@ -58,8 +58,6 @@ public:
         initialize("This module is the FemGui module."); // register with Python
     }
 
-    ~Module() override {}
-
 private:
     Py::Object invoke_method_varargs(void* method_def, const Py::Tuple& args) override
     {