HfArgumentParser doesn't recognize new list type hint syntax
Since Python 3.9 we can use generic types as type hints (e.g. `list[str]` instead of `typing.List[str]`), see also [PEP 585](https://www.python.org/dev/peps/pep-0585/). Currently this does not seem to work with the `HfArgumentParser`, but using the old `typing.List[str]` works.

Minimal example for an arguments data class:
```python
@dataclass
class Args:
  my_boring_argument_list: typing.List[str] # works
  my_cool_argument_list: list[str] # fails
```
I was able to pretty easily find the relevant piece of code and submitted a PR to fix it #15951 