POM 移除 Ribbon 相关依赖

<!-- LoadBalancer 必须引入 springcloud -->
<!-- 父pom引入springcloud 版本管理 -->  https://spring.io/projects/spring-cloud/  官网查看 boot 对应的 cloud 的版本
<dependencyManagement><dependency>    <groupId>org.springframework.cloud</groupId>    <artifactId>spring-cloud-dependencies</artifactId>    <version>${spring-cloud.version}</version>    <type>pom</type>    <scope>import</scope></dependency>
<dependencyManagement><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency><!-- 提供了RestTemplate支持 -->
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId>
</dependency><!-- na