Dataloader getitem not working for DreamboothDatasets
### Describe the bug

 Dataloader getitem is not working as before (see example of [DreamboothDatasets](https://github.com/huggingface/peft/blob/main/examples/lora_dreambooth/train_dreambooth.py#L451C14-L529))
moving Datasets to 2.8.0 solved the issue.

### Steps to reproduce the bug

1- using DreamBoothDataset to load some images 
2- error after loading when trying to visualise the images 

### Expected behavior

I was expecting a numpy array of the image

### Environment info

- Platform: Linux-5.10.147+-x86_64-with-glibc2.29
- Python version: 3.8.10
- PyArrow version: 9.0.0
- Pandas version: 1.3.5