dask_cudf.read_csv doesn't support StringIO

`dask_cudf.read_csv()` is calling `cudf.read_csv()` internally.
However, dask_cudf.read_csv() doesn't support StringIO input.

Description of api mislead (it seems copied over from cudf.read_csv())
```
path : str, path object, or file-like object
Either a path to a file (a str, pathlib.Path, or
py._path.local.LocalPath), URL (including http, ftp, and S3 locations),
or any object with a read() method (such as builtin open() file
handler function or StringIO).
```
Currently, StringIO input falls into https://github.com/rapidsai/cudf/blob/branch-23.04/python/dask_cudf/dask_cudf/io/csv.py#L99