audio column not saved correctly after resampling
## Describe the bug
After resampling the audio column, saving with save_to_disk doesn't seem to save with the correct type. 

## Steps to reproduce the bug
- load a subset of common voice dataset (48Khz)
- resample audio column to 16Khz
- save with save_to_disk()
- load with load_from_disk()

## Expected results
I expected that after saving the data, and then loading it back in, the audio column has the correct dataset.Audio type (i.e. same as before saving it)
{'accent': Value(dtype='string', id=None),
 'age': Value(dtype='string', id=None),
 'audio': Audio(sampling_rate=16000, mono=True, _storage_dtype='string', id=None),
 'client_id': Value(dtype='string', id=None),
 'down_votes': Value(dtype='int64', id=None),
 'gender': Value(dtype='string', id=None),
 'locale': Value(dtype='string', id=None),
 'path': Value(dtype='string', id=None),
 'segment': Value(dtype='string', id=None),
 'sentence': Value(dtype='string', id=None),
 'up_votes': Value(dtype='int64', id=None)}

## Actual results
Audio column does not have the right type
{'accent': Value(dtype='string', id=None),
 'age': Value(dtype='string', id=None),
 'audio': {'bytes': Value(dtype='binary', id=None),
  'path': Value(dtype='string', id=None)},
 'client_id': Value(dtype='string', id=None),
 'down_votes': Value(dtype='int64', id=None),
 'gender': Value(dtype='string', id=None),
 'locale': Value(dtype='string', id=None),
 'path': Value(dtype='string', id=None),
 'segment': Value(dtype='string', id=None),
 'sentence': Value(dtype='string', id=None),
 'up_votes': Value(dtype='int64', id=None)}

## Environment info
<!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
- `datasets` version: 1.17.0
- Platform: linux
- Python version:
- PyArrow version:
