AsyncChannel and AsyncThrowingChannel can hang tasks when that task is cancelled

[phausler]

let channel = AsyncChannel<Int>()
let task = Task {
  print("awaiting")
  await channel.send(1)
  print("done sending")
}
try! await Task.sleep(nanoseconds: 1_000_000_000)
task.cancel()
print("cancelled task")

https://forums.swift.org/t/leaking-tasks-if-a-channel-receiver-is-no-longer-listening/56330