cli.lwp3.repl: fix crash on Windows

Bleak on Windows doesn't cast data to bytes, so we have to do it ourselves.

Author: dlech

pybricksdev/cli/lwp3/repl.py

@@ -145,7 +145,7 @@ async def welcome():
                 logger.exception("bad input:")
             else:
                 logger.info("sending: %s", msg)
-                await client.write_gatt_char(LWP3_HUB_CHARACTERISTIC_UUID, msg)
+                await client.write_gatt_char(LWP3_HUB_CHARACTERISTIC_UUID, bytes(msg))
 
         logger.info("disconnecting...")