Discord.py sur heroku bot musique

Bonjour, J'ai un gros problème j'ai héberger mon bot sur heroku et quand j'ai voulu écouter de la musique ça ne marche pas alors que si je fais manuellement sans l'héberger ça marche expliquer moi svp.

Mon code:

music = {}
ytdl = youtube_dl.YoutubeDL()


class Video:
    def __init__(self, link):
        video = ytdl.extract_info(link, download=False)
        video_format = video["formats"][0]
        self.url = video["webpage_url"]
        self.stream_url = video_format["url"]
        self.title = video['title']
        self.duration = video['duration']
        self.thumbnail = video['thumbnail']
        return


def play_song(clients, queue, song):
    source = discord.PCMVolumeTransformer(discord.FFmpegPCMAudio(song.stream_url,
                                                                 before_options="-reconnect 1 -reconnect_streamed 1 -reconnect_delay_max 5"))

    def next(_):
        if len(queue) > 0:
            new_song = queue[0]
            del queue[0]
            play_song(clients, queue, new_song)
        else:
            asyncio.run_coroutine_threadsafe(clients.disconnect(), bot.loop)

    clients.play(source, after=next)

@bot.command()
async def play(ctx, url):
    if not ctx.message.author.voice:
        await ctx.send(" {} Vous devez vous connectez a un salon vocal !".format("<:no_entry:862022003639713892>"))
        return
    else:
        clients = ctx.guild.voice_client

        if clients and clients.channel:
            video = Video(url)
            music[ctx.guild].append(video)
        else:
            channels = ctx.message.author.voice.channel
            video = Video(url)
            music[ctx.guild] = []
            clients = await channels.connect()
            embed = discord.Embed(title="**Je met cette vidéo !**", color=0xFF0000, url=url)
            embed.set_author(name=ctx.author.name, icon_url=ctx.author.avatar_url)
            embed.set_thumbnail(url=video.thumbnail)
            embed.add_field(name="Titre :", value=video.title, inline=True)
            embed.add_field(name="Durée :", value=f"{video.duration}s", inline=True)
            await ctx.send(embed=embed)
            play_song(clients, music[ctx.guild], video)