torchvision.ImageFolder type hint need update to include Path type

The type hint of root in ImageFolder in torchvion is str, but it also support pathlib.Path type, this will result in pyright warning, so seems we should update the type hint to root: str | Path?

 def __init__(
            self,
            root: str,
            transform: Optional[Callable] = None,
            target_transform: Optional[Callable] = None,
            loader: Callable[[str], Any] = default_loader,
            is_valid_file: Optional[Callable[[str], bool]] = None,
    ):

cc @pmeier

Start at the ImageFolder.init entry point shown in the issue and inspect how the root parameter is annotated and used. Check the existing type-checking or test coverage around ImageFolder, then verify that pathlib.Path is accepted without the reported pyright warning. Done means the annotation reflects the supported inputs and relevant checks pass.