[Bug Report] Validate Select doesn't working when I click out the option box

### Element UI version
2.15.5

### OS/Browsers version
chrome 97.0

### Vue version
2.6.14

### Reproduction Link
https://codepen.io/haitn7620/pen/poWQmGJ

### Steps to reproduce
Click to the option box and click out the option box

### What is Expected?
Validate required doesn't working. Only works when I changed value

### What is actually happening?
I hope that when I click outside, it will tell me that I have to choose