text: Title: Save nparray as list
  Body: ### Describe the bug
  
  When I use the `map` function to convert images into features, datasets saves nparray as a list. Some people use the `set_format` function to convert the column back, but doesn't this lose precision?
  
  ### Steps to reproduce the bug
  
  the map function
  ```python
  def convert_image_to_features(inst, processor, image_dir):
      image_file = inst["image_url"]
      file = image_file.split("/")[-1]
      image_path = os.path.join(image_dir, file)
      image = Image.open(image_path)
      image = image.convert("RGBA")
  
      inst["pixel_values"] = processor(images=image, return_tensors="np")["pixel_values"]
      return inst
  ```
  
  main function
  ```python
  map_fun = partial(
        convert_image_to_features, processor=processor, image_dir=image_dir
    )
  ds = ds.map(map_fun, batched=False, num_proc=20)
  print(type(ds[0]["pixel_values"])
  ```
  
  ### Expected behavior
  
  (type < list>) 
  
  ### Environment info
  
  - `datasets` version: 2.16.1
  - Platform: Linux-4.19.91-009.ali4000.alios7.x86_64-x86_64-with-glibc2.35
  - Python version: 3.11.5
  - `huggingface_hub` version: 0.23.4
  - PyArrow version: 14.0.2
  - Pandas version: 2.1.4
  - `fsspec` version: 2023.10.0