Casting error in _send_request

[pkolbeck]

develop branch
importing dripline in the dl-py develop container.

Encountering this error, happens in get as well.
seems to be a typing problem possibly having to do with the pybind11 definition of the MsgRequest class in message_pybind.hh

https://github.com/driplineorg/dripline-python/blob/c0e1e1cfb333969347a59480815fd337dcf0c695/module_bindings/dripline_core/message_pybind.hh#L78

>>> interface.cmd("roach2_interface","is_running")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.12/site-packages/dripline/core/interface.py", line 151, in cmd
    reply_pkg = self._send_request( msgop=op_t.cmd, target=endpoint, specifier=specifier, lockout_key=lockout_key, payload=payload )
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/dripline/core/interface.py", line 76, in _send_request
    a_request.lockout_key = lockout_key if lockout_key is not None else ""
    ^^^^^^^^^^^^^^^^^^^^^
RuntimeError: bad lexical cast: source type value could not be interpreted as target
>>>