remove redundant void

src/App/DocumentObjectGroupPyImp.cpp

@@ -32,7 +32,7 @@
 using namespace App;
 
 // returns a string which represent the object e.g. when printed in python
-std::string DocumentObjectGroupPy::representation(void) const
+std::string DocumentObjectGroupPy::representation() const
 {
     return std::string("<group object>");
 }