add Firmware version request on Bootnotification accepted

EVCB_OCPP.WSServer/ProtalServer.cs

@@ -20,6 +20,7 @@ using System.Net.WebSockets;
 using System.Net;
 using System.Text;
 using EVCB_OCPP.WSServer.Service.WsService;
+using System.ServiceModel.Channels;
 
 namespace EVCB_OCPP.WSServer
 {
@@ -700,6 +701,12 @@ namespace EVCB_OCPP.WSServer
 
                                     await messageService.SendChangeConfigurationRequest(
                                         session.ChargeBoxId, key: "TimeOffset", value: "+08:00");
+
+                                    await messageService.SendDataTransferRequest(
+                                        session.ChargeBoxId, 
+                                        messageId:"ID_FirmwareVersion",
+                                        vendorId: "Phihong Technology",
+                                        data: string.Empty);
                                 }
                                 else
                                 {