Start building against Spring Data Kay snapshots

See gh-14328

spring-boot-project/spring-boot-dependencies/pom.xml

@@ -155,7 +155,7 @@
 		<spring-amqp.version>2.0.6.BUILD-SNAPSHOT</spring-amqp.version>
 		<spring-batch.version>4.0.1.RELEASE</spring-batch.version>
 		<spring-cloud-connectors.version>2.0.2.RELEASE</spring-cloud-connectors.version>
-		<spring-data-releasetrain.version>Kay-SR9</spring-data-releasetrain.version>
+		<spring-data-releasetrain.version>Kay-BUILD-SNAPSHOT</spring-data-releasetrain.version>
 		<spring-hateoas.version>0.25.0.RELEASE</spring-hateoas.version>
 		<spring-integration.version>5.0.7.RELEASE</spring-integration.version>
 		<spring-kafka.version>2.1.8.RELEASE</spring-kafka.version>