Fix #232 by adding explicit setup of Node.js, as suggested in ts-grap…

…hviz/setup-graphviz#578

.github/workflows/python-app.yml

@@ -38,6 +38,10 @@ jobs:
         python -m pip install --upgrade pip
         python -m pip install pytest
         python -m pip install interrogate
+    - name: Setup Node for Graphviz and JavaScript converter
+      uses: actions/setup-node@v4
+      with:
+        node-version: 18
     - name: Setup Graphviz
       uses: ts-graphviz/setup-graphviz@v1
     - name: Show Node.js version