bump xmlutil (#9505)

fixes broken surrogate pairs

gradle/kotlinx.versions.toml

@@ -1,7 +1,7 @@
 [versions]
 kotlin_version = "1.8.21"
 serialization_version = "1.5.0"
-xml_serialization_version = "0.85.0"
+xml_serialization_version = "0.86.0"
 
 [libraries]
 reflect = { module = "org.jetbrains.kotlin:kotlin-reflect", version.ref = "kotlin_version" }