Fix Gradle deprecation warnings and clean up some code warnings (#812)

* Fix Gradle deprecation warnings and clean up some code warnings

* Fixing build

* try disable required signing

* Back to nebula 11.4.0

* Update to Kotlin 2

* Remove dependsOn that no longer exists

---------

Co-authored-by: pbakker <$(git --no-pager log --format=format:'%ae' -n 1)>

Author: paulbakker

build.gradle

@@ -20,7 +20,7 @@ import org.jetbrains.kotlin.gradle.tasks.KotlinCompilationTask
  */
 
 plugins {
-    id 'org.jetbrains.kotlin.jvm' version "1.9.25" apply false
+    id 'org.jetbrains.kotlin.jvm' version "2.1.20" apply false
     id 'com.netflix.nebula.netflixoss' version '11.4.0'
     id "org.jmailen.kotlinter" version "5.0.1"
 }
@@ -31,7 +31,7 @@ allprojects {
 
     ext {
         Versions = [
-                KOTLIN_VERSION: '1.9.25'
+                KOTLIN_VERSION: '2.1.20'
         ]
     }
 
@@ -53,6 +53,8 @@ allprojects {
         testImplementation 'org.assertj:assertj-core:3.27.+'
         testImplementation 'org.junit.jupiter:junit-jupiter'
         testImplementation 'org.junit.jupiter:junit-jupiter-params'
+        testRuntimeOnly("org.junit.platform:junit-platform-launcher")
+
     }
 
     tasks.withType(Test).configureEach {