Update changelog for 1.2.3 release (#2409)
Update changelog for 1.2.3 release (#2409)


GoogleCloudPlatform/spring-cloud-gcp,spring-cloud/spring-cloud-gcp,spring-cloud/spring-cloud-gcp,spring-cloud/spring-cloud-gcp,GoogleCloudPlatform/spring-cloud-gcp,GoogleCloudPlatform/spring-cloud-gcp,GoogleCloudPlatform/spring-cloud-gcp,spring-cloud/spring-cloud-gcp,GoogleCloudPlatform/spring-cloud-gcp