add missing callback in ObjectToStringComposer

alib2str/src/object/ObjectToStringComposer.cpp

@@ -54,6 +54,8 @@ auto ObjectToStringComposerVoid = ObjectBaseDispatcher::RegistratorWrapper<void,
 auto ObjectToStringComposerAnyObjectSet = ObjectBaseDispatcher::RegistratorWrapper<void, AnyObject < std::set < Object > > >(ObjectToStringComposer::compose);
+auto ObjectToStringComposerAnyObjectPair = ObjectBaseDispatcher::RegistratorWrapper<void, AnyObject < std::pair < Object, Object > > >(ObjectToStringComposer::compose);
+
 auto ObjectToStringComposerAnyObjectUnsigned = ObjectBaseDispatcher::RegistratorWrapper<void, AnyObject < unsigned > >(ObjectToStringComposer::compose);
 auto ObjectToStringComposerObjectsPair = ObjectBaseDispatcher::RegistratorWrapper<void, container::ObjectsPair < Object, Object > >(ObjectToStringComposer::compose);