ci: don’t commit css if nothing has changed

.github/workflows/tailwindcss.yml

@@ -9,17 +9,22 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Install dependencies
       working-directory: app/static
-      run: npm install
+      run: npm ci
     - name: Build CSS
       working-directory: app/static
       run: npx tailwindcss -o css/main.css --minify
     - name: Commit and push changes
       run: |
-        git config --global user.email "github-actions@github.com"
-        git config --global user.name "Github Actions"
-        git add app/static/
-        git commit --allow-empty -m "Minifed CSS"
-        git push  
+        git config --global user.email "actions@github.com"
+        git config --global user.name "GitHub Actions"
+
+        if output="$(git status --porcelain)" && [ -z "$output" ]; then
+            echo "Nothing to commit."
+        else 
+            git add app/static/
+            git commit -m "Minifed CSS"
+            git push
+        fi