Send connection_lost even if we do not have an open serial connection

Author: puddly

zigpy_deconz/api.py

@@ -488,6 +488,8 @@ async def disconnect(self):
         if self._uart is not None:
             await self._uart.disconnect()
             self._uart = None
+        else:
+            self._app.connection_lost(None)
 
         self._app = None