Don't encode lists as strings when using `Value("string")`
Should we close this PR? since the original issue has to do with metrics that have been moved to `evaludate` I think we can close this one _The documentation is not available anymore as the PR was closed or merged._
Following https://github.com/huggingface/datasets/pull/3456#event-5792250497 it looks like `datasets` can silently convert lists to strings using `str()`, instead of raising an error.

This PR fixes this and should fix the issue with WER showing low values if the input format is not right.