[api]: Bump org.jetbrains.kotlin:kotlin-allopen from 1.9.10 to 1.9.20

Bumps [org.jetbrains.kotlin:kotlin-allopen](https://github.com/JetBrains/kotlin) from 1.9.10 to 1.9.20.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.9.10...v1.9.20)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-allopen
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

build.gradle.kts

@@ -6,7 +6,7 @@ import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 buildscript {
     dependencies {
         classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:1.9.20")
-        classpath("org.jetbrains.kotlin:kotlin-allopen:1.9.10")
+        classpath("org.jetbrains.kotlin:kotlin-allopen:1.9.20")
         classpath("com.adarshr:gradle-test-logger-plugin:4.0.0")
     }