Fix `save_cache` version in `config.yml`
# What does this PR do?

In #22204, I changed the `restore_cache` to `v0.6` but forgot to change `save_cache`. In consequence, no cache is saved/loaded, and the 2 jobs spend 5 minutes to install things:

<img width="716" alt="Screenshot 2023-06-22 101905" src="https://github.com/huggingface/transformers/assets/2521628/c796d958-ef9c-4066-bb46-3009be7a8fcc">


This PR fixes this and save money/credit we spend on CircleCI .... Please don't punish me 😭 
_The documentation is not available anymore as the PR was closed or merged._