Update node version in 'autoprefixer.yml' workflow (#964)

Co-authored-by: Emruz Hossain <hossainemruz@gmail.com>

.github/workflows/autoprefixer.yml

@@ -13,7 +13,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v4
         with:
-          node-version: "15.x"
+          node-version: "20.x"
 
       - name: Run autoprefixer
         run: |