Bump kotlin-stdlib from 1.4.20 to 1.6.0

Bumps [kotlin-stdlib](https://github.com/JetBrains/kotlin) from 1.4.20 to 1.6.0.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.6.0/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.4.20...v1.6.0)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -5,7 +5,7 @@
     <modelVersion>4.0.0</modelVersion>
 
     <properties>
-        <kotlin.version>1.4.20</kotlin.version>
+        <kotlin.version>1.6.0</kotlin.version>
         <java.version>1.8</java.version>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven-surefire-plugin.version>2.22.2</maven-surefire-plugin.version>