fix(deps): update dependency org.jetbrains.kotlin:kotlin-serialization to v2.0.21

Author: renovate[bot]

buildSrc/build.gradle.kts

@@ -9,7 +9,7 @@ dependencies {
     implementation(platform("org.jetbrains.kotlin:kotlin-bom:2.0.21"))
 
     implementation("org.jetbrains.kotlin:kotlin-gradle-plugin:2.0.21")
-    implementation("org.jetbrains.kotlin:kotlin-serialization:2.0.20")
+    implementation("org.jetbrains.kotlin:kotlin-serialization:2.0.21")
 
     implementation("io.gitlab.arturbosch.detekt:detekt-gradle-plugin:1.23.7")
     implementation("org.jmailen.gradle:kotlinter-gradle:4.4.1")