Polish voice messages support for bots and add webhook support

[GDjkhp]

Please let us use this instead of the traditional file uploads, and possibly add support IS_VOICE_MESSAGE flag for webhooks.

# Convert MP3 to Opus OGG
audio = AudioSegment.from_mp3("voice.mp3")
buffer = io.BytesIO()
audio.export(buffer, format="ogg", codec="libopus")
buffer.seek(0)
file_size = buffer.getbuffer().nbytes

async with aiohttp.ClientSession() as session:
    # Step 1: Request upload URL
    headers = {
        "Authorization": f"Bot {BOT_TOKEN}",
        "Content-Type": "application/json"
    }
    data = {
        "files": [{"filename": "voice-message.ogg", "file_size": file_size, "id": "2"}]
    }
    async with session.post(f'https://discord.com/api/v10/channels/{CHANNEL_ID}/attachments', headers=headers, json=data) as response:
        if response.status != 200:
            print(f"Failed to get upload URL: {await response.text()}")
            return
        upload_data = await response.json()

    # Step 2: Upload the file
    upload_url = upload_data['attachments'][0]['upload_url']
    upload_filename = upload_data['attachments'][0]['upload_filename']
    async with session.put(upload_url, data=buffer.getvalue()) as response:
        if response.status != 200:
            print(f"Failed to upload file: {await response.text()}")
            return

    # Experiment 1: Send voice message as a Discord bot
    data = {
        "flags": 8192,
        "attachments": [{
            "id": "0",
            "filename": "voice-message.ogg",
            "uploaded_filename": upload_filename,
            "duration_secs": int(audio.duration_seconds),
            "waveform": base64.b64encode(bytes([128] * 256)).decode('utf-8') # Dummy waveform
        }]
    }
    async with session.post(f'https://discord.com/api/v10/channels/{CHANNEL_ID}/messages', headers=headers, json=data) as response:
        if response.status != 200:
            print(f"Failed to send voice message: {await response.text()}")
        else:
            print("Voice message sent successfully!")

    # Experiment 2: Send voice message via webhook (500: Internal Server Error)
    headers = {
        "Content-Type": "application/json"
    }
    async with session.post(WEBHOOK_URL, headers=headers, json=data) as response:
        if response.status != 204:
            print(f"Failed to send voice message: {await response.text()}")
        else:
            print("Voice message sent successfully via webhook!")

Reference: https://gist.github.com/HDR/7d5d4ce8bbe4b715d788a9bc9f99e02d