concurrent pipe sends no longer allowed

[efanibi25]

I had to surround windows pipe sends in a lock context because of this change
https://github.com/python/cpython/blob/3.12/Lib/multiprocessing/connection.py

   def _send_bytes(self, buf):
            if self._send_ov is not None:
                # A connection should only be used by a single thread
                raise ValueError("concurrent send_bytes() calls "
                                 "are not supported")

This is the commit it is referenced
python/cpython#107219