Add OffComBR
Hello @hugoabonizio, thanks for the contribution.
Regarding the fake data, you can generate it manually.
Running the `python datasets-cli dummy_data datasets/offcombr` should give you instructions on how to manually create the dummy data.
For reference, here is a spec for `.arff` files : https://www.cs.waikato.ac.nz/ml/weka/arff.html @lhoestq again the failing tests doesn't seem to be related merging since the CI is fixed on master
Add [OffComBR](https://github.com/rogersdepelle/OffComBR) from [Offensive Comments in the Brazilian Web: a dataset and baseline results](https://sol.sbc.org.br/index.php/brasnam/article/view/3260/3222) paper.

But I'm having a hard time generating dummy data since the original dataset extion is `.arff` and the [_create_dummy_data function](https://github.com/huggingface/datasets/blob/a4aeaf911240057286a01bff1b1d75a89aedd57b/src/datasets/commands/dummy_data.py#L185) doesn't allow it.