update 更新 readme 版本号错误问题

README.md

@@ -4,7 +4,7 @@
 [![License](https://img.shields.io/badge/License-MIT-blue.svg)](https://gitee.com/JavaLionLi/RuoYi-Vue-Plus/blob/master/LICENSE)
 [![使用IntelliJ IDEA开发维护](https://img.shields.io/badge/IntelliJ%20IDEA-提供支持-blue.svg)](https://www.jetbrains.com/?from=RuoYi-Vue-Plus)
 <br>
-[![RuoYi-Vue-Plus](https://img.shields.io/badge/RuoYi_Vue_Plus-4.2.0-beta1-success.svg)](https://gitee.com/JavaLionLi/RuoYi-Vue-Plus)
+[![RuoYi-Vue-Plus](https://img.shields.io/badge/RuoYi_Vue_Plus-4.2.0_beta1-success.svg)](https://gitee.com/JavaLionLi/RuoYi-Vue-Plus)
 [![Spring Boot](https://img.shields.io/badge/Spring%20Boot-2.6-blue.svg)]()
 [![JDK-8+](https://img.shields.io/badge/JDK-8-green.svg)]()
 [![JDK-11](https://img.shields.io/badge/JDK-11-green.svg)]()