Support `#` in config names
https://huggingface.co/datasets/bigcode/commitpackft/viewer/c%23

> Could not read the parquet files: https://huggingface.co/datasets/bigcode/commitpackft/resolve/refs%2Fconvert%2Fparquet/c#/train/0000.parquet
> Error code:   FileSystemError

<img width="951" alt="Capture d’écran 2024-01-29 à 10 20 47" src="https://github.com/huggingface/datasets-server/assets/1676121/e7f5b2d8-d121-4409-aae6-d66c0707191d">


Reported here: https://huggingface.co/datasets/bigcode/commitpackft/discussions/4#65b5ca59e02a17f0f86da0b4


Support `#` in config names: https://huggingface.co/datasets/bigcode/commitpackft/viewer/c%23

> Could not read the parquet files: https://huggingface.co/datasets/bigcode/commitpackft/resolve/refs%2Fconvert%2Fparquet/c#/train/0000.parquet
> Error code:   FileSystemError

<img width="951" alt="Capture d’écran 2024-01-29 à 10 20 47" src="https://github.com/huggingface/datasets-server/assets/1676121/e7f5b2d8-d121-4409-aae6-d66c0707191d">


Reported here: https://huggingface.co/datasets/bigcode/commitpackft/discussions/4#65b5ca59e02a17f0f86da0b4

