Update require-v-for-key.js

Author: armano2

lib/rules/require-v-for-key.js

@@ -17,7 +17,7 @@ const utils = require('../utils')
 
 module.exports = {
   meta: {
-    type: 'suggestion',
+    type: 'problem',
     docs: {
       description: 'require `v-bind:key` with `v-for` directives',
       category: 'essential',