UPDMRTF — modify reference to UML 2.3 to UML 2.4.1

UML2.3 should be changed to UML 2.4.1unless there is inevitable reason, since UML2.4.1 has been standardized as IS.

Response:- At the time the standard was published UML 2.3 was the current version of UML. A change to UML 2.4.1 would invalidate the references to UML in the XMI resulting in a major change to the standard. It is envisaged that a major release i.e. UPDM 3.0 aka UAF 1 would update the references to the latest versions of UML and SysML available.