方案：将两个的版本都提高即可解决

Mybatis—plus的依赖文件

        <dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.3</version></dependency><!-- generator --><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-generator</artifactId><version>3.5.3</version></dependency>