Upgrade to Activemq 5.15.9

Closes gh-16373

Author: snicoll

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

@@ -33,7 +33,7 @@
 	<properties>
 		<main.basedir>${basedir}/../..</main.basedir>
 		<!-- Dependency versions -->
-		<activemq.version>5.15.8</activemq.version>
+		<activemq.version>5.15.9</activemq.version>
 		<antlr2.version>2.7.7</antlr2.version>
 		<appengine-sdk.version>1.9.71</appengine-sdk.version>
 		<artemis.version>2.4.0</artemis.version>