[bug] Issue in CLIP model code for ch16

### Enter the chapter number

Ch16

### Enter the page number

674

### What is the cell's number in the notebook

cell 39 in clip section

### Enter the environment you are using to run the notebook

Colab

### Describe your issue

get_image_features and get_text_features used to return a plain torch.FloatTensor, but now they output a BaseModelOutputWithPooling. We cannot use .norm with this object, leading to an error in this line:

```python
image_features /= image_features.norm(dim=1, keepdim=True)
```

with the error being:

```python
AttributeError: 'BaseModelOutputWithPooling' object has no attribute 'norm'
```

### If you found a workaround, describe it here

I have found a workaround after taking a look at different discussions in huggingface

```python
output = self.clip_model.get_image_features(**inputs)
if not isinstance(output, torch.Tensor):
output = output.pooler_output
```
adding the following line fixes the issue
```python
image_features = image_features.pooler_output
```