Bump org.jetbrains.kotlin:kotlin-bom from 1.8.20 to 1.8.21 (#540)

Bumps [org.jetbrains.kotlin:kotlin-bom](https://github.com/JetBrains/kotlin) from 1.8.20 to 1.8.21.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.8.21/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.8.20...v1.8.21)

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

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

splunk-otel-android/build.gradle.kts

@@ -47,7 +47,7 @@ val otelAlphaVersion = "$otelVersion-alpha"
 val otelInstrumentationAlphaVersion = "1.26.0-alpha-SNAPSHOT"
 
 dependencies {
-    implementation(platform("org.jetbrains.kotlin:kotlin-bom:1.8.20"))
+    implementation(platform("org.jetbrains.kotlin:kotlin-bom:1.8.21"))
     implementation("androidx.appcompat:appcompat:1.6.1")
     implementation("androidx.core:core:1.10.0")
     implementation("androidx.navigation:navigation-fragment:2.5.3")