Bump kotlin.version from 1.6.10 to 1.6.20 (#737)

Bumps `kotlin.version` from 1.6.10 to 1.6.20.

Updates `kotlin-stdlib-jdk8` from 1.6.10 to 1.6.20
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/commits)

Updates `kotlin-test` from 1.6.10 to 1.6.20
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/commits)

Updates `kotlin-maven-plugin` from 1.6.10 to 1.6.20

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib-jdk8
  dependency-type: direct:development
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-test
  dependency-type: direct:development
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

testsuite/extra/pom.xml

@@ -30,7 +30,7 @@
   <name>SmallRye: MicroProfile Config Test Suite - Extra</name>
 
   <properties>
-    <kotlin.version>1.6.10</kotlin.version>
+    <kotlin.version>1.6.20</kotlin.version>
   </properties>
 
   <dependencies>