Updates kotlin to 2.2.21

Fixes gh-570

Author: spencergibb

pom.xml

@@ -30,6 +30,7 @@
 		<docs.main>${project.artifactId}</docs.main>
 		<spring-boot.version>4.0.0-RC1</spring-boot.version>
 		<spring-cloud-build.version>5.0.0-SNAPSHOT</spring-cloud-build.version>
+		<kotlin.version>2.2.21</kotlin.version>
 		<docs.resources.dir>${project.build.directory}/build-docs</docs.resources.dir>
 		<docs.classes.dir>${project.build.directory}/build-docs-classes</docs.classes.dir>
 		<refdocs.build.directory>${project.build.directory}/refdocs/</refdocs.build.directory>