初始化项目时node版本老出问题
## What happens?
运行yarn create egg --type=simple
node为8.x时 报如下错误
![image](https://user-images.githubusercontent.com/16096724/103664456-41fd7c00-4fad-11eb-970a-bec6db10964a.png)

node为12.x报如下错误
![image](https://user-images.githubusercontent.com/16096724/103664548-5ccff080-4fad-11eb-8c4b-ead9a1be3388.png)

## How To Reproduce

**Steps to reproduce the behavior:**
1.yarn create egg --type=simple

**Expected behavior**
1.成功创建egg项目

## Context
- **Node Version**: 8.x 10.x 12.x
- **Egg Version**: 2.29.1
- **Platform**: macOS 10.15.7
