chore!: drop Node.js 12 support

As eslint-plugin-vue has dropped it in v9.

Author: haoqunjiang

Diff for: package.json

@@ -55,6 +55,6 @@
     "vue-eslint-parser": "^9.0.0"
   },
   "engines": {
-    "node": "^12.22.0 || ^14.17.0 || >=16.0.0"
+    "node": "^14.17.0 || >=16.0.0"
   }
 }