Update mdbook

Author: amousset

.github/workflows/gh-pages.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Setup mdBook
         uses: peaceiris/actions-mdbook@v1
         with:
-          mdbook-version: '0.4.31'
+          mdbook-version: '0.4.32'
           #mdbook-version: 'latest'
 
       - run: mdbook build