Bump KOTLIN_VERSION from 1.8.10 to 1.8.20 (ethereum-lists#796)

Bumps `KOTLIN_VERSION` from 1.8.10 to 1.8.20.

Updates `org.jetbrains.kotlin:kotlin-gradle-plugin` from 1.8.10 to 1.8.20

Updates `org.jetbrains.kotlin:kotlin-stdlib` from 1.8.10 to 1.8.20

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-gradle-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  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>
Co-authored-by: ligi <ligi@ligi.de>

build.gradle

@@ -1,6 +1,6 @@
 buildscript {
  ext {
- KOTLIN_VERSION = "1.8.10"
+ KOTLIN_VERSION = "1.8.20"
  KETHEREUM_VERSION = "0.85.7"
  }