Upgrade to Spring Kafka 2.1.5.RELEASE

Closes gh-12775

Author: wilkinsona

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

@@ -156,7 +156,7 @@
 		<spring-data-releasetrain.version>Kay-SR6</spring-data-releasetrain.version>
 		<spring-hateoas.version>0.24.0.RELEASE</spring-hateoas.version>
 		<spring-integration.version>5.0.4.RELEASE</spring-integration.version>
-		<spring-kafka.version>2.1.4.RELEASE</spring-kafka.version>
+		<spring-kafka.version>2.1.5.RELEASE</spring-kafka.version>
 		<spring-ldap.version>2.3.2.RELEASE</spring-ldap.version>
 		<spring-plugin.version>1.2.0.RELEASE</spring-plugin.version>
 		<spring-restdocs.version>2.0.1.RELEASE</spring-restdocs.version>