Update kotlinx.serialization to v1.9.0

Author: solrbot

gradle/libs.versions.toml

@@ -149,7 +149,7 @@ kotlinx-atomicfu = "0.27.0"
 kotlinx-browser = "0.3"
 kotlinx-coroutines = "1.10.1"
 kotlinx-datetime = "0.6.2"
-kotlinx-serialization = "1.8.0"
+kotlinx-serialization = "1.9.0"
 ktor = "3.1.0"
 langchain4j = "0.35.0"
 # @keep Link checker version used in ref-guide