Merge pull request #5206 from upupming/fix/demo-declare-sass

fix(demo): declare the sass dependency vite's scss compilation needs

Author: JoviDeCroock

demo/package-lock.json

@@ -10,6 +10,7 @@
   "devDependencies": {
     "@babel/plugin-proposal-class-properties": "^7.0.0-beta.55",
     "@babel/plugin-proposal-decorators": "^7.4.0",
+    "sass": "^1.53.0",
     "vite": "^5.4.10"
   },
   "dependencies": {