manually add furo to yml

.github/workflows/docs.yml

@@ -32,7 +32,7 @@ jobs:
           python -m pip install --upgrade pip
           pip install poetry
           poetry install --with docs --without dev,lint --no-interaction
-          python -m pip install --upgrade --no-cache-dir setuptools sphinx readthedocs-sphinx-ext
+          python -m pip install --upgrade --no-cache-dir setuptools sphinx readthedocs-sphinx-ext furo
           python -m pip install -r docs/requirements.txt
       - name: Check for broken links
         run: |