modified close method according to recommendation in asyncio docs, re…

…solved TypeError

alicat/util.py

@@ -181,7 +181,8 @@ async def _handle_communication(self, command: str) -> Optional[str]:
     async def close(self) -> None:
         """Close the TCP connection."""
         if self.open:
-            await self.connection['writer'].close()
+            self.connection['writer'].close()
+            await self.connection['writer'].wait_closed()
         self.open = False