chore: bump kotlin from 2.3.20 to 2.4.0

Bumps `kotlin` from 2.3.20 to 2.4.0.

Updates `org.jetbrains.kotlin.plugin.compose` from 2.3.20 to 2.4.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/compare/v2.3.20...v2.4.0)

Updates `org.jetbrains.kotlin.plugin.serialization` from 2.3.20 to 2.4.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/compare/v2.3.20...v2.4.0)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin.plugin.compose
  dependency-version: 2.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin.plugin.serialization
  dependency-version: 2.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

gradle/libs.versions.toml

@@ -12,7 +12,7 @@ coroutines = "1.10.2"
 junit = "4.13.2"
 junit5 = "5.11.4"
 junitPlatform = "1.11.4"
-kotlin = "2.3.20"
+kotlin = "2.4.0"
 # standalone per KSP 2.0+ guidance — NOT kotlinVersion-kspVersion; easy
 # to miss during Kotlin upgrades since it no longer tracks the Kotlin version.
 ksp = "2.3.9"