Delete todo comment in _up_to_3_worker.py.

I think I was talking about wanting to move the list loop into pydantic-core, by parsing this through a TypeAdapter(list[Command]) instead of a TypeAdapter(Command). That might be worth trying, but not in this PR.

robot-server/robot_server/persistence/_migrations/_up_to_3_worker.py

@@ -85,7 +85,6 @@ def migrate_commands_for_run(
             _legacy_pickle.loads(old_commands_bytes) if old_commands_bytes else []
         )
 
-        # TODO Fold the list into this?
         parsed_commands: typing.Iterable[commands.Command] = (
             commands.CommandAdapter.validate_python(c) for c in old_commands
         )