Build(deps): Bump org.jetbrains.kotlin:kotlin-bom from 2.3.20 to 2.3.21

Bumps [org.jetbrains.kotlin:kotlin-bom](https://github.com/JetBrains/kotlin) from 2.3.20 to 2.3.21.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.3.20...v2.3.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-bom
  dependency-version: 2.3.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

app/build.gradle.kts

@@ -41,7 +41,7 @@ android {
 }
 
 dependencies {
-    implementation(platform("org.jetbrains.kotlin:kotlin-bom:2.3.20"))
+    implementation(platform("org.jetbrains.kotlin:kotlin-bom:2.3.21"))
     implementation("androidx.core:core-ktx:1.18.0")
 
     // Compose BOM (Bill of Materials)