Fix pandoc

.github/workflows/sphinx.yml

@@ -13,9 +13,9 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v3
-      - uses: docker://pandoc/core:2.9
       - name: Install dependencies
         run: |
+          sudo apt install pandoc
           python -m pip install --upgrade pip
           pip install sphinx sphinx_rtd_theme nbsphinx
       - name: Sphinx build