Fix yield for crd3
Modified the `_generate_examples` function to consider all the turns for a chunk id as a single example
Modified the features accordingly

```
"turns": [
                        {
                            "names": datasets.features.Sequence(datasets.Value("string")),
                            "utterances": datasets.features.Sequence(datasets.Value("string")),
                            "number": datasets.Value("int32"),
                        }
                    ],
                }
```

I wasn't able to run `datasets-cli dummy_data datasets` command. Is there a workaround for this? 