chore(gradle): small dependency updates & kotlin opt in

Author: xeruf

gradle/build.gradle.kts

@@ -11,7 +11,7 @@ plugins {
     id("scripts-task")
 
     id("com.github.ben-manes.versions") version "0.38.0"
-    id("se.patrikerdes.use-latest-versions") version "0.2.15"
+    id("se.patrikerdes.use-latest-versions") version "0.2.16"
 }
 
 val gameName by extra { property("socha.gameName") as String }
@@ -251,13 +251,17 @@ subprojects {
                 freeCompilerArgs = listOf("-Xjvm-default=all")
             }
         }
+        
+        compileTestKotlin.get().kotlinOptions {
+            freeCompilerArgs = freeCompilerArgs.plus("-Xopt-in=kotlin.RequiresOptIn")
+        }
     }
 }
 
 allprojects {
     repositories {
-        jcenter()
-        maven("http://dist.wso2.org/maven2")
+        mavenCentral()
+        maven("https://dist.wso2.org/maven2")
     }
 
     if (this.name in documentedProjects) {

player/build.gradle.kts

@@ -96,7 +96,8 @@ tasks {
         doLast {
             // required by gradle to distinguish the test build from
             execDir.resolve("settings.gradle").createNewFile()
-            val command = arrayListOf(if(OperatingSystem.current() == OperatingSystem.WINDOWS) "./gradlew.bat" else "./gradlew",
+            val command = arrayListOf(
+                    "./gradlew${if(OperatingSystem.current().isWindows) ".bat" else ""}",
                     "shadowJar", "--quiet", "--offline")
             val process = ProcessBuilder(command).directory(execDir)
                     .redirectOutput(execDir.resolve("player-shadowJar-build.log"))

sdk/build.gradle.kts

@@ -27,7 +27,7 @@ configurations.archives.get().artifacts.removeIf { it.name == "testConfig" }
 
 dependencies {
     api(kotlin("stdlib"))
-    api("com.thoughtworks.xstream", "xstream", "1.4.15")
+    api("com.thoughtworks.xstream", "xstream", "1.4.16")
     api("jargs", "jargs", "1.0")
     api("ch.qos.logback", "logback-classic", "1.2.3")