Update Kotlin, KSP and Compose Compiler to v2.1.21 (#75)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

gradle/libs.versions.toml

@@ -7,7 +7,7 @@ androidx-activityCompose = "1.8.2"
 jetpack-compose-bom = "2025.01.00"
 compose-plugin = "1.7.3"
 koin = "4.0.4"
-kotlin = "2.1.20"
+kotlin = "2.1.21"
 ktor = "3.1.3"
 kamel = "1.0.3"