Update GitHub Actions to use v4 of GitHub Pages artifacts

Author: joshuavial

.github/workflows/deploy.yml

@@ -30,10 +30,10 @@ jobs:
         run: mdbook build
 
       - name: Setup Pages
-        uses: actions/configure-pages@v3
+        uses: actions/configure-pages@v4
 
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v4
         with:
           path: 'book'
 
@@ -46,4 +46,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v2
+        uses: actions/deploy-pages@v4