Update to Kotlin 1.4.32 and remove unused Gradle plugin.

Author: charleskorn

settings.gradle.kts

@@ -20,9 +20,8 @@ rootProject.name = "kaml"
 
 pluginManagement {
     plugins {
-        kotlin("jvm") version "1.4.30"
-        kotlin("multiplatform") version "1.4.30"
-        kotlin("plugin.serialization") version "1.4.30"
+        kotlin("multiplatform") version "1.4.32"
+        kotlin("plugin.serialization") version "1.4.32"
         id("com.github.ben-manes.versions") version "0.38.0"
     }
 }