Update Kotlin [1.5.0 -> 1.6.0], coroutines [1.5.2 -> 1.6.0-RC]

Author: greenrobot-team

build.gradle

@@ -22,8 +22,8 @@ buildscript {
         essentials_version = '3.1.0'
         junit_version = '4.13.2'
         mockito_version = '3.8.0'
-        kotlin_version = '1.5.0'
-        coroutines_version = '1.5.2'
+        kotlin_version = '1.6.0'
+        coroutines_version = '1.6.0-RC'
         dokka_version = '1.4.32'
 
         println "version=$ob_version"