Docs versioning no longer working

[jeromekelleher]

We don't see the version of msprime that the docs are for any more - something has change in the JupyterBook config.

This may be an issue with the upstream build in the website repo, though

Related: https://github.com/tskit-dev/tstrait/issues/88

[daikitag]

@jeromekelleher I will try fixing the issue

[jeromekelleher]

We might need to make changes in the tskit-site code, I'm not sure: https://github.com/tskit-dev/tskit-site/blob/main/.github/workflows/build-deploy.yml