Vue Wizard表单单选按钮验证

Question

我正在使用由Cristi Jora整合Element UI的vue-form-wizard，基本示例就在这里

    Vue.use(VueFormWizard)
new Vue({
  el: '#app',
  data: {
    formInline: {
      user: '',
      region: '',
      gender: ''
    },
    rules: {
      user: [{
        required: true,
        message: 'Please input Activity name',
        trigger: 'blur'
      }, {
        min: 3,
        max: 5,
        message: 'Length should be 3 to 5',
        trigger: 'blur'
      }],
      region: [{
        required: true,
        message: 'Please select Activity zone',
        trigger: 'change'
      }],
    }
  },
  methods: {
    onComplete: function() {
      alert('Yay. Done!');
    },
    validateFirstStep() {
      return new Promise((resolve, reject) => {
        this.$refs.ruleForm.validate((valid) => {
          resolve(valid);
        });
      })

    }
  }
})

https://jsfiddle.net/bt5dhqtf/409

但我无法验证单选按钮，请帮助我:(

这是我的例子 https://jsfiddle.net/bt5dhqtf/884/