Upgrade to Kotlin 1.9.20-RC

Closes gh-37926

Author: wilkinsona

gradle.properties

@@ -9,7 +9,7 @@ commonsCodecVersion=1.16.0
 hamcrestVersion=2.2
 jacksonVersion=2.15.3
 junitJupiterVersion=5.10.0
-kotlinVersion=1.9.10
+kotlinVersion=1.9.20-RC
 mavenVersion=3.9.4
 nativeBuildToolsVersion=0.9.27
 springFrameworkVersion=6.1.0-RC1