VisibleDeprecationWarning when using `set_format("numpy")`
{'login': 'Rocketknight1', 'id': 12866554, 'node_id': 'MDQ6VXNlcjEyODY2NTU0', 'avatar_url': 'https://avatars.githubusercontent.com/u/12866554?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/Rocketknight1', 'html_url': 'https://github.com/Rocketknight1', 'followers_url': 'https://api.github.com/users/Rocketknight1/followers', 'following_url': 'https://api.github.com/users/Rocketknight1/following{/other_user}', 'gists_url': 'https://api.github.com/users/Rocketknight1/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/Rocketknight1/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/Rocketknight1/subscriptions', 'organizations_url': 'https://api.github.com/users/Rocketknight1/orgs', 'repos_url': 'https://api.github.com/users/Rocketknight1/repos', 'events_url': 'https://api.github.com/users/Rocketknight1/events{/privacy}', 'received_events_url': 'https://api.github.com/users/Rocketknight1/received_events', 'type': 'User', 'site_admin': False}
[{'id': 1935892857, 'node_id': 'MDU6TGFiZWwxOTM1ODkyODU3', 'url': 'https://api.github.com/repos/huggingface/datasets/labels/bug', 'name': 'bug', 'color': 'd73a4a', 'default': True, 'description': "Something isn't working"}]
{'login': 'Rocketknight1', 'id': 12866554, 'node_id': 'MDQ6VXNlcjEyODY2NTU0', 'avatar_url': 'https://avatars.githubusercontent.com/u/12866554?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/Rocketknight1', 'html_url': 'https://github.com/Rocketknight1', 'followers_url': 'https://api.github.com/users/Rocketknight1/followers', 'following_url': 'https://api.github.com/users/Rocketknight1/following{/other_user}', 'gists_url': 'https://api.github.com/users/Rocketknight1/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/Rocketknight1/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/Rocketknight1/subscriptions', 'organizations_url': 'https://api.github.com/users/Rocketknight1/orgs', 'repos_url': 'https://api.github.com/users/Rocketknight1/repos', 'events_url': 'https://api.github.com/users/Rocketknight1/events{/privacy}', 'received_events_url': 'https://api.github.com/users/Rocketknight1/received_events', 'type': 'User', 'site_admin': False}
[{'login': 'Rocketknight1', 'id': 12866554, 'node_id': 'MDQ6VXNlcjEyODY2NTU0', 'avatar_url': 'https://avatars.githubusercontent.com/u/12866554?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/Rocketknight1', 'html_url': 'https://github.com/Rocketknight1', 'followers_url': 'https://api.github.com/users/Rocketknight1/followers', 'following_url': 'https://api.github.com/users/Rocketknight1/following{/other_user}', 'gists_url': 'https://api.github.com/users/Rocketknight1/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/Rocketknight1/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/Rocketknight1/subscriptions', 'organizations_url': 'https://api.github.com/users/Rocketknight1/orgs', 'repos_url': 'https://api.github.com/users/Rocketknight1/repos', 'events_url': 'https://api.github.com/users/Rocketknight1/events{/privacy}', 'received_events_url': 'https://api.github.com/users/Rocketknight1/received_events', 'type': 'User', 'site_admin': False}, {'login': 'lhoestq', 'id': 42851186, 'node_id': 'MDQ6VXNlcjQyODUxMTg2', 'avatar_url': 'https://avatars.githubusercontent.com/u/42851186?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/lhoestq', 'html_url': 'https://github.com/lhoestq', 'followers_url': 'https://api.github.com/users/lhoestq/followers', 'following_url': 'https://api.github.com/users/lhoestq/following{/other_user}', 'gists_url': 'https://api.github.com/users/lhoestq/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/lhoestq/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/lhoestq/subscriptions', 'organizations_url': 'https://api.github.com/users/lhoestq/orgs', 'repos_url': 'https://api.github.com/users/lhoestq/repos', 'events_url': 'https://api.github.com/users/lhoestq/events{/privacy}', 'received_events_url': 'https://api.github.com/users/lhoestq/received_events', 'type': 'User', 'site_admin': False}]
I just opened a PR and I verified that the code you provided doesn't show any deprecation warning :)
Code to reproduce:

```
from datasets import load_dataset
dataset = load_dataset("glue", "mnli")

from transformers import AutoTokenizer
tokenizer = AutoTokenizer.from_pretrained('distilbert-base-cased')

def tokenize_function(dataset):
    return tokenizer(dataset['premise'])

tokenized_datasets = dataset.map(tokenize_function, batched=True, remove_columns=dataset['train'].features)

tokenized_datasets.set_format("numpy")

tokenized_datasets['train'][5:8]
```
Outputs:

```
python3.9/site-packages/datasets/formatting/formatting.py:167: VisibleDeprecationWarning: Creating an ndarray from ragged nested sequences (which is a list-or-tuple of lists-or-tuples-or ndarrays with different lengths or shapes) is deprecated. If you meant to do this, you must specify 'dtype=object' when creating the ndarray
  return np.array(array, copy=False, **self.np_array_kwargs)
```
{'url': 'https://api.github.com/repos/huggingface/datasets/issues/3084/reactions', 'total_count': 0, '+1': 0, '-1': 0, 'laugh': 0, 'hooray': 0, 'confused': 0, 'heart': 0, 'rocket': 0, 'eyes': 0}