Support Kotlin 2.3.20

[hfhbd]

Description of the issue
Kotlin 2.3.20 was released on 2026-03-16: https://github.com/JetBrains/kotlin/releases/tag/v2.3.20

CodeQL does not support Kotlin 2.3.20 yet, due to small changes in the Kotlin compiler plugin api.