TypeError: Value.__init__() missing 1 required positional argument: 'dtype'
### Describe the bug

ds = load_dataset(
    "./xxx.py",
    name="default",
    split="train",
)

The datasets does not support debugging locally anymore...

### Steps to reproduce the bug

```
from datasets import load_dataset

ds = load_dataset(
    "./repo.py",
    name="default",
    split="train",
)

for item in ds:
    print(item)
```

It works fine for "username/repo", but it does not work for "./repo.py" when debugging locally...
Running above code template will report TypeError: Value.__init__() missing 1 required positional argument: 'dtype'

### Expected behavior

fix this bug

### Environment info

python 3.10 datasets==2.21