Update production-diagram.yml

hardcoded the Hugo version to avoid issue as mentioned in peaceiris/actions-hugo#605

.github/workflows/production-diagram.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Setup Hugo
       uses: peaceiris/actions-hugo@v2
       with:
-          hugo-version: '1.101.0'
+          hugo-version: '0.101.0'
           extended: true
     - name: Install autoprefixer
       run:  npm install -D --save autoprefixer