Update kotlin version to 1.3.70

Author: oshai

build.gradle.kts

@@ -2,7 +2,7 @@ import org.jetbrains.dokka.gradle.DokkaTask
 import java.util.Date
 
 plugins {
-    kotlin("multiplatform") version "1.3.50"
+    kotlin("multiplatform") version "1.3.70"
     id("com.jfrog.bintray") version "1.8.4"
     id("org.jetbrains.dokka") version "0.10.0"
     `maven-publish`