Remove deadlock-causing broadcast synchronisation

	def __init__(self) -> None:

		super().__init__()

		self._ready = anyio.Condition()

		self.task_status: anyio.abc.TaskStatus|None = None

	async def shutdown_hook(self) -> None:

		if self.task_status is not None:

			self.task_status.started()

			self.task_status = None

		async with self._ready:

			self._ready.notify_all()

	async def post_send_hook(self) -> None:

		# Await notification of either a receiver waiting or the broadcaster closing

		# This is necessary to delay returning until a filter has had a chance to return

		# a result.

		async with self._ready:

			await self._ready.wait()

class Runner: