expanduser in save_to_disk
{'login': 'RmZeta2718', 'id': 42400165, 'node_id': 'MDQ6VXNlcjQyNDAwMTY1', 'avatar_url': 'https://avatars.githubusercontent.com/u/42400165?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/RmZeta2718', 'html_url': 'https://github.com/RmZeta2718', 'followers_url': 'https://api.github.com/users/RmZeta2718/followers', 'following_url': 'https://api.github.com/users/RmZeta2718/following{/other_user}', 'gists_url': 'https://api.github.com/users/RmZeta2718/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/RmZeta2718/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/RmZeta2718/subscriptions', 'organizations_url': 'https://api.github.com/users/RmZeta2718/orgs', 'repos_url': 'https://api.github.com/users/RmZeta2718/repos', 'events_url': 'https://api.github.com/users/RmZeta2718/events{/privacy}', 'received_events_url': 'https://api.github.com/users/RmZeta2718/received_events', 'type': 'User', 'site_admin': False}
[]
[]
`save_to_disk` should indeed expand `~`. Marking it as a "good first issue".
### Describe the bug

save_to_disk() does not expand `~`

1. `dataset = load_datasets("any dataset")`
2. `dataset.save_to_disk("~/data")`
3. a folder named "~" created in current folder
4. FileNotFoundError is raised, because the expanded path does not exist (`/home/<user>/data`)

related issue https://github.com/huggingface/transformers/issues/10628

### Steps to reproduce the bug

As described above.

### Expected behavior

expanduser correctly

### Environment info

- datasets 2.10.1
- python 3.10
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