Update kotlin to 1.3.30

Author: yuyakaido

build.gradle

@@ -1,7 +1,7 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
-    ext.kotlin_version = '1.3.21'
+    ext.kotlin_version = '1.3.30'
     repositories {
         google()
         jcenter()