[Java] Bump JUnit to 5.13.0.

Author: vyazelenko

gradle/libs.versions.toml

@@ -8,7 +8,7 @@ httpcore = "4.4.14"
 jqwik = "1.9.2"
 jmh = "1.37"
 json = "20250517"
-junit = "5.12.2"
+junit = "5.13.0"
 mockito = "5.18.0"
 plexus = "3.3.0"
 shadow = "8.3.6"