ci: use static hugo version to fix issue with latest alias

See https://github.com/peaceiris/actions-hugo/issues/⁠652.

Author: radhermit

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
     - name: Setup Hugo
       uses: peaceiris/actions-hugo@v3
       with:
-        hugo-version: 'latest'
+        hugo-version: "0.139.4"
         extended: true
 
     - name: Build