ci: use Jammy Jellyfish in GitHub Actions

- Update GitHub Actions workflow to use the latest Ubuntu release

Author: bresilla

.github/workflows/book.yml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   deploy_site:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
 
@@ -22,4 +22,4 @@ jobs:
         uses: peaceiris/actions-gh-pages@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
-          publish_dir: ./docs
+          publish_dir: ./docs