Update serialization to v1.8.0

Author: renovate[bot]

gradle/libs.versions.toml

@@ -1,7 +1,7 @@
 [versions]
 kotlin = "2.1.0"
 coroutines = "1.9.0"
-serialization = "1.7.3"
+serialization = "1.8.0"
 okhttp = "5.0.0-alpha.14" # Major version is locked by Tachiyomi extensions
 javalin = "6.3.0"
 jackson = "2.18.2" # jackson version locked by javalin, ref: `io.javalin.core.util.OptionalDependency`