Upgrade to JUnit Jupiter 5.4 RC2

Issue: spring-projects#22308

Author: sbrannen

build.gradle

@@ -34,7 +34,7 @@ ext {
 	hsqldbVersion        = "2.4.1"
 	jackson2Version      = "2.9.8"
 	jettyVersion         = "9.4.14.v20181114"
-	junit5Version        = "5.4.0-RC1"
+	junit5Version        = "5.4.0-RC2"
 	kotlinVersion        = "1.3.20"
 	log4jVersion         = "2.11.1"
 	nettyVersion         = "4.1.33.Final"