Fix checkstyle violation: remove unused import

Author: wilkinsona

spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java

@@ -53,7 +53,6 @@
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigUtils;
 import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.event.ContextRefreshedEvent;
 import org.springframework.context.event.SimpleApplicationEventMulticaster;