Change model from ElevenMusic --> acestep to align with pollinations.ai requirements

app.py

@@ -587,7 +587,7 @@ async def gensfx(
         prompt, MAX_MEDIA_PROMPT_CHARS, MAX_MEDIA_PROMPT_BYTES, "Audio prompt"
     )
     await check_audio_rate_limit(request, authorization, x_client_id)
-    url = f"https://gen.pollinations.ai/audio/{prompt}?model=elevenmusic&key={PKEY}"
+    url = f"https://gen.pollinations.ai/audio/{prompt}?model=acestep&key={PKEY}"
     async with httpx.AsyncClient(timeout=None) as client:
         response = await client.get(url)
     body_text = ""