Update GitHub Actions to use latest versions

Author: julianu

.github/workflows/publish.yml

@@ -20,15 +20,15 @@ jobs:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Set up Quarto
         uses: quarto-dev/quarto-actions/setup@v2
         with:
           tinytex: true
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: '3.14'
 
@@ -43,10 +43,10 @@ jobs:
           path: ./textbook/
 
       - name: Upload Pages artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v5
         with:
           path: textbook/_book
 
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v5