Update gh-pages.yml

Adds the autoprefixer tool to the GitHub Actions configuration.

Author: Logofile

.github/workflows/gh-pages.yml

@@ -22,7 +22,7 @@ jobs:
           extended: true
 
       - name: Install Dependencies
-        run: npm install -g postcss postcss-cli
+        run: npm install autoprefixer postcss postcss-cli
 
       - name: Build
         run: hugo --minify