Bump org.jetbrains.kotlin:kotlin-stdlib from 1.9.20 to 1.9.21

Bumps [org.jetbrains.kotlin:kotlin-stdlib](https://github.com/JetBrains/kotlin) from 1.9.20 to 1.9.21.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.9.20...v1.9.21)

---
updated-dependencies:
- 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>

build.gradle.kts

@@ -56,7 +56,7 @@ subprojects {
     apply(plugin = "com.github.johnrengelman.shadow")
 
     dependencies {
-        val kotlin = compileOnly("org.jetbrains.kotlin:kotlin-stdlib:1.9.20")
+        val kotlin = compileOnly("org.jetbrains.kotlin:kotlin-stdlib:1.9.21")
         project.ext["kotlin_version"] = kotlin!!.version
 
         compileOnly("org.jetbrains:annotations:24.1.0")