evaluation result changes after `datasets` version change
Hi! The GH/no-namespace datasets versioning is synced with the version of the `datasets` lib, which means that the `wikiann` script was modified between the two compared versions. In this scenario, you can ensure reproducibility by pinning the script version, which is done by passing `revision="x.y.z"` (e.g. `revision="2.2.0"`) to `load_dataset.`

## Describe the bug
evaluation result changes after `datasets` version change

## Steps to reproduce the bug
1. Train a model on WikiAnn
2. reload the ckpt -> test accuracy becomes same as eval accuracy
3. such behavior is gone after downgrading `datasets`

https://colab.research.google.com/drive/1kYz7-aZRGdayaq-gDTt30tyEgsKlpYOw?usp=sharing

## Expected results
evaluation result shouldn't change before/after `datasets` version changes

## Actual results
evaluation result changes before/after `datasets` version changes

## Environment info
<!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
- `datasets` version: 2.3.2
- Platform: colab
- Python version: 3.7.13
- PyArrow version: 6.0.1

Q. How could the evaluation result change before/after `datasets` version changes?