How to update SPItemEventReceiver assembly version for a list in SharePoint?

public override void FeatureActivated(SPFeatureReceiverProperties properties)
    {
        foreach (SPWeb web in site.AllWebs)
        {
            SPListCollection webListCollection = web.Lists;

            foreach (SPList myList in webListCollection)
            {
                if (myList.Title == "Lab Reports")
                {
                    SPEventReceiverDefinitionCollection receivers = myList.EventReceivers;
                    SPEventReceiverDefinition receiver = receivers.Add();
                    receiver.Name = "PostUpdateLabReport";
                    receiver.Assembly = "LabReportEventHandlers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=1111111111111";
                    receiver.Class = "LabReportEventHandlers.LabReportsHandler";
                    receiver.Type = SPEventReceiverType.ItemUpdated;
                    receiver.Update();
                    break;
                }
            }

            web.Dispose();
        }
    }