Update junit version required for System Rules library

Signed-off-by: Khushboo Rajput <[email protected]>

build.gradle

@@ -331,7 +331,10 @@ dependencies {
     def jacksonVersion = "${versions.jackson}"
     def jacksonDataBindVersion = "${versions.jackson_databind}"
     def nettyVersion = "${versions.netty}"
-    def junitVersion = "${versions.junit}"
+    // def junitVersion = "${versions.junit}"
+    // library System Rules requires minimum junit version 4.9, the current
+    // junit version used in Opensearch is 4.13.2
+    def junitVersion = "4.9"
     def log4jVersion = "${versions.log4j}"
     def protobufVersion = "${versions.protobuf}"
     def guavaVersion = "${versions.guava}"