Fix document publishing GitHub Action

It seems that Chromium is no longer found automatically. See also
puppeteer/puppeteer#9533.

.github/workflows/publish.yaml

@@ -22,6 +22,11 @@ jobs:
       - name: Install mermaid diagram filter
         run: sudo npm install --global mermaid-filter
 
+      - name: Ensure Puppeteer (Chromium API) is fully installed
+        run: |
+          sudo /usr/local/lib/node_modules/puppeteer/install.js
+          echo sudo snap install chromium
+
       - name: Build documentation
         run: cd doc/doxygen-root && make && touch html/.nojekyll