Remember to remove serial writer. (#2209)

Author: janiversen

pymodbus/transport/serialtransport.py

@@ -46,6 +46,7 @@ def close(self, exc: Exception | None = None) -> None:
             self.poll_task = None
         else:
             self.async_loop.remove_reader(self.sync_serial.fileno())
+            self.async_loop.remove_writer(self.sync_serial.fileno())
         self.sync_serial.close()
         self.sync_serial = None  # type: ignore[assignment]
         if exc: