Revert "Bump kotlinx-serialization from 1.6.3 to 1.7.0 (#578)" (#584)

Author: StaehliJ

gradle/libs.versions.toml

@@ -31,7 +31,7 @@ junit = "4.13.2"
 kotlin = "2.0.0"
 kotlinx-coroutines = "1.8.1"
 kotlinx-kover = "0.8.1"
-kotlinx-serialization = "1.7.0"
+kotlinx-serialization = "1.6.3"
 ktor = "2.3.11"
 mockk = "1.13.11"
 okhttp = "4.12.0"