Updated Gradle and Kotlin version

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {

    ext.dokka_version = '0.9.16'

    ext.kotlin_version = '1.2.41'

    ext.kotlin_version = '1.2.50'

    repositories {

        jcenter()

        google()

    }

    dependencies {

        classpath 'com.android.tools.build:gradle:3.1.2'

        classpath 'com.android.tools.build:gradle:3.1.3'

        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

        classpath "org.jetbrains.dokka:dokka-android-gradle-plugin:${dokka_version}"

    }