add serialization template to Action::Quantity

opm/parser/eclipse/EclipseState/Schedule/Action/Condition.hpp

@@ -46,6 +46,13 @@ public:
         return quantity == data.quantity &&
                args == data.args;
     }
+
+    template<class Serializer>
+    void serializeOp(Serializer& serializer)
+    {
+        serializer(quantity);
+        serializer(args);
+    }
 };