Spec deployment fails in GitHub Actions

```
Run bikeshed update
Bikeshed now requires Python 3.12 or higher; you are on 3.10.19.
    For instructions on how to set up a pyenv with 3.12, see:
    https://speced.github.io/bikeshed/#installing
Error: Process completed with exit code 1.
```

https://github.com/w3c/csswg-drafts/actions/runs/20038502180/job/57466292039