Upgrade to Spring Kafka 2.3.0.RC1

Closes gh-17902

Author: wilkinsona

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

@@ -190,7 +190,7 @@
 		<spring-framework.version>5.2.0.RC2</spring-framework.version>
 		<spring-hateoas.version>1.0.0.RC2</spring-hateoas.version>
 		<spring-integration.version>5.2.0.RC1</spring-integration.version>
-		<spring-kafka.version>2.3.0.BUILD-SNAPSHOT</spring-kafka.version>
+		<spring-kafka.version>2.3.0.RC1</spring-kafka.version>
 		<spring-ldap.version>2.3.2.RELEASE</spring-ldap.version>
 		<spring-plugin.version>2.0.0.M1</spring-plugin.version>
 		<spring-restdocs.version>2.0.3.RELEASE</spring-restdocs.version>