🐛remove extra comma in vue3/package.json (umijs#1383)

Author: gongshun

examples/vue3/package.json

@@ -23,7 +23,7 @@
     "eslint": "^6.7.2",
     "eslint-plugin-vue": "^7.0.0-0",
     "less": "^3.0.4",
-    "less-loader": "^5.0.0",
+    "less-loader": "^5.0.0"
   },
   "eslintConfig": {
     "root": true,