THRIFT-5560: use JUnit 5 for all Java lib tests (#2574)

diff --git a/lib/java/gradle.properties b/lib/java/gradle.properties
index 8d4f0e4..dfa29fe 100644
--- a/lib/java/gradle.properties
+++ b/lib/java/gradle.properties
@@ -30,7 +30,7 @@
 slf4j.version=1.7.35
 servlet.version=4.0.1
 tomcat.embed.version=9.0.43
-junit.version=4.13.2
+junit.version=5.8.2
 mockito.version=1.10.19
 javax.annotation.version=1.3.2
 commons-lang3.version=3.12