Merge pull request #1930 from nextcloud/dependabot/gradle/org.jetbrains.kotlin-kotlin-gradle-plugin-1.6.21

Bump kotlin-gradle-plugin from 1.6.20 to 1.6.21

build.gradle

@@ -24,7 +24,7 @@
 buildscript {
 
     ext {
-        kotlinVersion = '1.6.20'
+        kotlinVersion = '1.6.21'
     }
 
     repositories {