Update gh-pages.yml

due to failure to download the seemingly anomalous 0.139.5 release. See: https://github.com/gohugoio/hugo/releases/tag/v0.139.5

.github/workflows/gh-pages.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Setup Hugo
         uses: peaceiris/actions-hugo@v2
         with:
-          hugo-version: "latest"
+          hugo-version: "0.139.4"
           extended: true
 
       - name: Build and minify with Hugo, using GH Pages baseURL