Remove stderr_file associated with the client.

def remove_stderr_file(self):
        """Remove stderr_file associated with the client."""
        try:
            # Defer closing the stderr_handle until the client
            # is closed because jupyter_client needs it open
            # while it tries to restart the kernel
            self.stderr_handle.close()
            os.remove(self.stderr_file)
        except Exception:
            pass