Use `dash==2.8.1` for now for daily CI
# What does this PR do?

Use `das==2.8.1` for now for daily CI. Currently daily CI jobs all fail, for example, [this job run](https://github.com/huggingface/transformers/actions/runs/4443525103/jobs/7800913606)

Issue reported [here](https://github.com/plotly/dash/issues/2460)
_The documentation is not available anymore as the PR was closed or merged._