Downgrade JUnit5

Because the test could not be executed for some reason.

Author: k163377

gradle/libs.versions.toml

@@ -3,7 +3,7 @@ kotlin = "1.9.25" # Mainly for CI, it can be rewritten by environment variable.
 jackson = "2.18.2"
 
 # test libs
-junit = "5.12.0"
+junit = "5.11.4"
 
 [libraries]
 kotlin-stdlib = { module = "org.jetbrains.kotlin:kotlin-stdlib" }