install graphviz

.github/workflows/book.yml

@@ -1,12 +1,8 @@
-# Simple workflow for deploying static content to GitHub Pages
-name: Deploy static content to Pages
+name: Update book
 
 on:
-  # Runs on pushes targeting the default branch
   push:
     branches: ["book"]
-
-  # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
 
 # Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
@@ -35,6 +31,8 @@ jobs:
         uses: actions/configure-pages@v5
       - name: Set up Python
         uses: actions/setup-python@v4
+      - name: Setup Graphviz
+        uses: ts-graphviz/setup-graphviz@v2
       - name: Install dependencies
         run: |
           pip install -r requirements.txt