Bug in `convert_to_diffuses`

Flagging bug here in `convert_to_diffuses` for quick fix.

```python
        transformer = FluxTransformer2DModel(guidance_embeds=has_guidance)
        transformer.load_state_dict(converted_transformer_state_dict, strict=True)
        
        if output_directory:
            transformer_path = os.path.join(output_directory,transformer) # <= should be "transformer"
```