[pipeline] VQA pipeline does not accept list as input
### System Info

- `transformers` version: 4.42.0.dev0
- Platform: Linux-5.15.146.1-microsoft-standard-WSL2-x86_64-with-glibc2.35
- Python version: 3.10.12
- Huggingface_hub version: 0.23.0
- Safetensors version: 0.4.3
- Accelerate version: not installed
- Accelerate config: not found
- PyTorch version (GPU?): 2.3.0+cpu (False)
- Tensorflow version (GPU?): not installed (NA)
- Flax version (CPU?/GPU?/TPU?): not installed (NA)
- Jax version: not installed
- JaxLib version: not installed
- Using distributed or parallel set-up in script?: no

### Who can help?

@Narsil @sijunhe 

### Information

- [ ] The official example scripts
- [X] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [X] My own task or dataset (give details below)

### Reproduction

```python
from transformers import pipeline
urls = ["https://huggingface.co/datasets/Narsil/image_dummy/raw/main/parrots.png", "https://huggingface.co/datasets/Narsil/image_dummy/raw/main/tree.png"]

oracle = pipeline(task="vqa", model="dandelin/vilt-b32-finetuned-vqa")
oracle(question="What's in the image?", image=urls, top_k=1)
```
(Truncated) error:
```---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[1], [line 11](vscode-notebook-cell:?execution_count=1&line=11)
      [8](vscode-notebook-cell:?execution_count=1&line=8) oracle = pipeline(task="vqa", model="dandelin/vilt-b32-finetuned-vqa", image_processor=image_processor)
      [9](vscode-notebook-cell:?execution_count=1&line=9) # for out in tqdm(oracle(question="What's in this image", image=dataset, top_k=1)):
     [10](vscode-notebook-cell:?execution_count=1&line=10) #     print(out)
---> [11](vscode-notebook-cell:?execution_count=1&line=11) oracle(question="What's in this image", image=urls, top_k=1)

File ~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:114, in VisualQuestionAnsweringPipeline.__call__(self, image, question, **kwargs)
    [107](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:107)     """
    [108](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:108)     Supports the following format
    [109](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:109)     - {"image": image, "question": question}
    [110](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:110)     - [{"image": image, "question": question}]
    [111](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:111)     - Generator and datasets
    [112](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:112)     """
    [113](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:113)     inputs = image
--> [114](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:114) results = super().__call__(inputs, **kwargs)
    [115](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:115) return results

File ~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/base.py:1224, in Pipeline.__call__(self, inputs, num_workers, batch_size, *args, **kwargs)
   [1220](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/base.py:1220) if can_use_iterator:
   [1221](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/base.py:1221)     final_iterator = self.get_iterator(
   [1222](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/base.py:1222)         inputs, num_workers, batch_size, preprocess_params, forward_params, postprocess_params
   [1223](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/base.py:1223)     )
-> [1224](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/base.py:1224)     outputs = list(final_iterator)
...
    [120](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:120)         inputs["question"], return_tensors=self.framework, padding=padding, truncation=truncation
    [121](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:121)     )
    [122](https://vscode-remote+wsl-002bubuntu-002d22-002e04.vscode-resource.vscode-cdn.net/home/blaccod/dev/lab24-env/lab24-multimodal-cardinality-estimation/~/dev/lab24-env/lib/python3.10/site-packages/transformers/pipelines/visual_question_answering.py:122)     image_features = self.image_processor(images=image, return_tensors=self.framework)

TypeError: string indices must be integers
```
This error is reproducible on the latest version (v4.41.2)

### Expected behavior

The pipeline should broadcast the same question on all images and execute the model on those image-question pair, as per the [documentation](https://huggingface.co/docs/transformers/en/main_classes/pipelines#transformers.VisualQuestionAnsweringPipeline)

Note: This currently works, but it is not as easy to use as passing the lists directly (and this doesn't allow passing the `dataset` directly like [this](https://huggingface.co/docs/transformers/v4.41.3/en/main_classes/pipelines#transformers.pipeline)):
```python
oracle([{"question": "What's in the image?", "image": url} for url in urls])
```