fix:fix Feign.Builder.class not found error

spring-cloud-tencent-starters/spring-cloud-tencent-feign/src/main/java/com/tencent/cloud/feign/PluggableFeignAutoConfiguration.java

@@ -29,11 +29,9 @@ import org.springframework.context.annotation.Configuration;
  * @author Haotian Zhang
  */
 @Configuration
-public class PluggableFeignAutoConfiguration {
-
-    @Configuration
 @ConditionalOnProperty(name = "com.tencent.cloud.feign.enabled", matchIfMissing = true)
-    static class PluggableFeignConfig {
+@ConditionalOnClass(Feign.class)
+public class PluggableFeignAutoConfiguration {
 
     @Bean
     @ConditionalOnMissingBean
@@ -42,5 +40,3 @@ public class PluggableFeignAutoConfiguration {
     }
 
 }
-
-}