Cannot load the dataset conll2012_ontonotesv5
Hi @cathyxl, thanks for reporting.

Indeed, we have recently updated the loading script of that dataset (and fixed that bug as well):
- #4002

That fix will be available in our next `datasets` library release. In the meantime, you can incorporate that fix by:
- installing `datasets` from our GitHub repo:
```bash
pip install git+https://github.com/huggingface/datasets#egg=datasets
```
- forcing the data files to be redownloaded
```python
ds = load_dataset('conll2012_ontonotesv5', 'english_v4', split="test", download_mode="force_redownload")
```

Feel free to re-open this issue if the problem persists.
## Describe the bug
Cannot load the dataset conll2012_ontonotesv5

## Steps to reproduce the bug
```python
# Sample code to reproduce the bug
from datasets import load_dataset
dataset = load_dataset('conll2012_ontonotesv5', 'english_v4', split="test")
print(dataset)

```

## Expected results
The datasets should be downloaded successfully

## Actual results
raise NonMatchingChecksumError(error_msg + str(bad_urls))
datasets.utils.info_utils.NonMatchingChecksumError: Checksums didn't match for dataset source files:
['https://md-datasets-cache-zipfiles-prod.s3.eu-west-1.amazonaws.com/zmycy7t9h9-1.zip']

## Environment info
<!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
- `datasets` version: 2.0.0
- Platform: Linux-5.4.0-88-generic-x86_64-with-glibc2.31
- Python version: 3.9.7
- PyArrow version: 7.0.0

