Upgrade to Kotlin 1.6.20-M1

Closes gh-10687

config/spring-security-config.gradle

@@ -113,7 +113,7 @@ tasks.withType(KotlinCompile).configureEach {
 		languageVersion = "1.6"
 		apiVersion = "1.6"
 		freeCompilerArgs = ["-Xjsr305=strict", "-Xsuppress-version-warnings"]
-		jvmTarget = "11"
+		jvmTarget = "17"
 	}
 }
 

gradle.properties

@@ -4,7 +4,7 @@ springBootVersion=2.4.2
 springFrameworkVersion=6.0.0-M2
 openSamlVersion=3.4.6
 version=6.0.0-SNAPSHOT
-kotlinVersion=1.6.10
+kotlinVersion=1.6.20-M1
 samplesBranch=6.0.x
 org.gradle.jvmargs=-Xmx3g -XX:+HeapDumpOnOutOfMemoryError
 org.gradle.parallel=true