Upgrade to Spring Boot 2.2.4

Author: snicoll

ci/images/releasescripts/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>2.2.0.RELEASE</version>
+		<version>2.2.4.RELEASE</version>
 		<relativePath/> <!-- lookup parent from repository -->
 	</parent>
 	<groupId>io.spring.concourse.releasescripts</groupId>