Update dependency autoprefixer to v10.4.21

Author: renovate[bot]

package-lock.json

@@ -49,7 +49,7 @@
     "@types/node": "22.7.4",
     "@types/react": "18.3.11",
     "@types/react-dom": "18.3.1",
-    "autoprefixer": "10.4.20",
+    "autoprefixer": "10.4.21",
     "eslint": "8.57.0",
     "eslint-config-next": "14.2.14",
     "postcss": "8.4.47",