Trying to fix CI

Author: coppolaemilio

.github/workflows/mdbook.yml

@@ -48,7 +48,7 @@ jobs:
       - name: Build with mdBook
         run: mdbook build
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v3
         with:
           path: ./book