updated workflow to install sphinxcontrib-bibtex

Author: AlePalu

.github/workflows/documentation.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/setup-python@v3
       - name: Install dependencies
         run: |
-          pip install sphinx sphinx_immaterial myst_parser
+          pip install sphinx sphinx_immaterial myst_parser sphinxcontrib-bibtex
       - name: Sphinx build
         run: |
           sphinx-build -M html . _build