Multi-voice generation failed: 模型 IndexTTS-1.5 缺少必要的文件: gpt.pth, config.yaml

### Custom Node Testing

- [x] I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)

### Expected Behavior

Multi-voice generation failed: 模型 IndexTTS-1.5 缺少必要的文件: gpt.pth, config.yaml。我已经按照readme装好环境和下好模型，出现了这样的报错。请问什么原因

### Actual Behavior

Multi-voice generation failed: 模型 IndexTTS-1.5 缺少必要的文件: gpt.pth, config.yaml。我已经按照readme装好环境和下好模型，出现了这样的报错。请问什么原因

### Steps to Reproduce

Multi-voice generation failed: 模型 IndexTTS-1.5 缺少必要的文件: gpt.pth, config.yaml。我已经按照readme装好环境和下好模型，出现了这样的报错。请问什么原因

### Debug Logs

```powershell
Multi-voice generation failed: 模型 IndexTTS-1.5 缺少必要的文件: gpt.pth, config.yaml。我已经按照readme装好环境和下好模型，出现了这样的报错。请问什么原因
```

### Other

_No response_