Read The Docs Build Failing

Getting this on builds:

```
Error
Config validation error in build.os. Value os not found.

git clone --depth 1 https://github.com/datafolklabs/cement.git .
git fetch origin --force --prune --prune-tags --depth 50 refs/heads/main:refs/remotes/origin/main
git checkout --force origin/main
git clean -d -f -f
```


Any help here would be really appreciated... Google not really helpful.