Remove unused import

Author: olegz

spring-cloud-function-adapters/spring-cloud-function-adapter-aws/src/main/java/org/springframework/cloud/function/adapter/aws/AWSLambdaUtils.java

@@ -33,7 +33,6 @@
 import org.springframework.http.HttpStatus;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
-import org.springframework.messaging.support.GenericMessage;
 import org.springframework.messaging.support.MessageBuilder;
 import org.springframework.util.StreamUtils;