Add sleep delay in post connect (#164)

Short delay added to avoid race condition with boot notification message on first connection/boot

custom_components/ocpp/api.py

@@ -347,6 +347,7 @@ async def handle_data_transfer(call):
 
         try:
             self.status = STATE_OK
+            await asyncio.sleep(2)
             await self.get_supported_features()
             if prof.REM in self._attr_supported_features:
                 await self.trigger_status_notification()