[Gradle] Update stable Kotlin version to 1.9.20 Graphql-kotlin benchmark

libraries/tools/gradle/regression-benchmarks/benchmarkScripts/graphql-kotlin.benchmark.kts

@@ -3,14 +3,14 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-// Quite big library written in Kotlin:
+// Relatively big library written in Kotlin:
 // - uses Spring boot
 // - uses Kotlin kapt
 @file:BenchmarkProject(
     name = "graphql-kotlin",
     gitUrl = "https://github.com/ExpediaGroup/graphql-kotlin.git",
     gitCommitSha = "7d1e5a3114e95a4e0d63a8c515e9e8e37d5c504c",
-    stableKotlinVersion = "1.9.10",
+    stableKotlinVersion = "1.9.20",
 )
 
 import java.io.File