问如何使用ValidationProvider上的字典(Vue.Js)自定义VeeValidate的“必需”错误消息

EN

import Vue from 'vue';
import App from './App.vue';
import './core/extensions';

new Vue({
  render: h => h(App),
}).$mount('#app');

import Vue from 'vue';
import VeeValidate, { Validator } from 'vee-validate';
import ptBR from 'vee-validate/dist/locale/pt_BR';

const dict = {
   messages: ptBR.messages,
   pt_BR: {
     custom: {
        cpf: {
          required: 'Favor preencher o cpf',
        },
      }
    },
  };

Vue.use(VeeValidate);

Validator.localize({ pt_BR: dict })

Validator.extend('cpf', (val) => {
     return false //just to test
});

<template>
    <div id="app">
     <ValidationObserver ref="observer">
         <ValidationProvider ref="cpfinput" rules="cpf" name="CPF">
            <myInput
              slot-scope="{ errors }"
              :errorProp="errors"
              name="cpf"
            />
          </ValidationProvider>
      </ValidationObserver>    
    </div>
</template>