Start building against Spring Integration 4.3.9 snapshots

See gh-8713

spring-boot-dependencies/pom.xml

@@ -151,7 +151,7 @@
 		<spring-batch.version>3.0.7.RELEASE</spring-batch.version>
 		<spring-data-releasetrain.version>Hopper-SR8</spring-data-releasetrain.version>
 		<spring-hateoas.version>0.20.0.RELEASE</spring-hateoas.version>
-		<spring-integration.version>4.3.8.RELEASE</spring-integration.version>
+		<spring-integration.version>4.3.9.BUILD-SNAPSHOT</spring-integration.version>
 		<spring-integration-java-dsl.version>1.1.4.RELEASE</spring-integration-java-dsl.version>
 		<spring-loaded.version>1.2.6.RELEASE</spring-loaded.version>
 		<spring-mobile.version>1.1.5.RELEASE</spring-mobile.version>