update kotest to JUnit 5 in testhelpers

Robolectric only has a JUnit 4 interface, however we are adapting it via
RobolectricExtension.kt. However this means we still require a reference
to JUnit4 in this specific testhelpers to do this.

Author: jkasten2

OneSignalSDK/build.gradle

@@ -17,7 +17,6 @@ buildscript {
         kotestVersion = '5.8.0'
         ktlintPluginVersion = '11.6.1'
         ktlintVersion = '1.0.1'
-        junitVersion = '4.13.2'
         // DO NOT upgrade for tests, using an old version so it matches AOSP
         tdunningJsonForTest = '1.0'
     }

OneSignalSDK/onesignal/testhelpers/build.gradle

@@ -38,8 +38,12 @@ android {
 dependencies {
     implementation(project(':OneSignal:core'))
 
-    implementation("junit:junit:$junitVersion")
-    implementation("io.kotest:kotest-runner-junit4:$kotestVersion")
+    // Only use for RobolectricExtension.kt,
+    // to bridge Robolectric's JUnit4 usage to Kotest's Junit 5
+    implementation("junit:junit:4.13.2")
+
+    implementation("io.kotest:kotest-runner-junit5:$kotestVersion")
+    implementation("io.kotest:kotest-runner-junit5-jvm:$kotestVersion")
     implementation("org.robolectric:robolectric:4.8.1")
     implementation("org.jetbrains.kotlin:kotlin-reflect:$kotlinVersion")
     implementation("io.mockk:mockk:1.13.2")