Bump Kotlin/Native version in KGP to 1.9.20-dev-6271

KT-59859
diff --git a/build.gradle.kts b/build.gradle.kts
index 7ae1c3d..cbd9be6f 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -102,7 +102,7 @@
 
 if (!project.hasProperty("versions.kotlin-native")) {
     // BEWARE! Bumping this version doesn't take an immediate effect on TeamCity: KTI-1107
-    extra["versions.kotlin-native"] = "1.9.20-dev-6128"
+    extra["versions.kotlin-native"] = "1.9.20-dev-6271"
 }
 
 val irCompilerModules = arrayOf(