ci: fix workflow by installing furo for Sphinx

Added the installation of `furo` to the CI workflow to resolve issues preventing the documentation build from running correctly. The `furo` theme provides a modern and responsive design for Sphinx documentation.

- Updated CI configuration to include `python -m pip install furo`.
- Ensured successful build and upload of Sphinx documentation using the Furo theme.

This fix addresses the workflow problem and enhances the appearance of the WML documentation.

.github/workflows/host_docs.yaml

@@ -30,6 +30,7 @@ jobs:
           # python -m pip install sphinxcontrib-apidoc
           python -m pip install sphinx-autoapi
           python -m pip install myst_parser
+          python -m pip install furo
 
       - name: make the sphinx docs
         run: |