Verify that the reader accepts not only filepath string but other expected input types as well

[Achaad]

The backend definition is following:
def open_dataset(self, filename_or_obj: str | os.PathLike[Any] | ReadBuffer[Any] | bytes | memoryview | AbstractDataStore, *, drop_variables: str | Iterable[str] | None = None, ) -> xr.Dataset:

Testing was performed with str type. We need to verify that other types would work correctly.