reddit_tifu dataset: Checksums didn't match for dataset source files
## Describe the bug
When loading the reddit_tifu dataset, it throws the exception "Checksums didn't match for dataset source files"


## Steps to reproduce the bug
```python
import datasets
from datasets import load_dataset

print(datasets.__version__)

# load_dataset('billsum')

load_dataset('reddit_tifu', 'short')
```


## Environment info
<!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
- `datasets` version: 1.17.0
- Platform: mac os
- Python version: Python 3.7.6
- PyArrow version: 3.0.0
