[Java] Upgrade to JUnit 5.12.0.

Author: vyazelenko

gradle/libs.versions.toml

@@ -9,7 +9,7 @@ httpcore = "4.4.14"
 jqwik = "1.9.2"
 jmh = "1.37"
 json = "20250107"
-junit = "5.11.4"
+junit = "5.12.0"
 mockito = "5.15.2"
 plexus = "3.3.0"
 shadow = "8.3.6"