Fix OpenStream return a closed stream

[shynome]

Description

i want to reuse StreamIdentifier after the parent dc closed, but the current code will return a broken datachannel with a closed stream

package main

import (
	"fmt"
	"time"

	"github.com/lainio/err2/try"
	"github.com/pion/webrtc/v3"
)

func main2() {

	var api *webrtc.API
	var pc *webrtc.PeerConnection
	defer pc.Close()

	var id uint16 = 0
	for {
		go func() {
			// id++
			params := &webrtc.DataChannelParameters{
				ID: &id,
			}
			dc := try.To1(
				api.NewDataChannel(pc.SCTP(), params))
			defer dc.Close()
			conn := try.To1(
				dc.Detach())

			fmt.Fprintln(conn, "woooooooooo")

			for {
				n := dc.BufferedAmount()
				if n == 0 {
					break
				}
			}
		}()
		time.Sleep(3 * time.Second)
	}
}

Reference issue

Fixes #...