Upgrade elasticsearch-rest-client to 6.5.4

There are no specific changes that we need. This is just to keep
up-to-date with the latest release. See the release notes [1] for
details.

[1] https://www.elastic.co/guide/en/elasticsearch/reference/current/release-notes-6.5.4.html

Upgrade the V6_5 test version accordingly in ElasticContainer.

Change-Id: Ifa420a55c519e738887771fefcd8f3ba6150508a
diff --git a/gerrit-elasticsearch/src/test/java/com/google/gerrit/elasticsearch/ElasticContainer.java b/gerrit-elasticsearch/src/test/java/com/google/gerrit/elasticsearch/ElasticContainer.java
index b35e66e..08e4678 100644
--- a/gerrit-elasticsearch/src/test/java/com/google/gerrit/elasticsearch/ElasticContainer.java
+++ b/gerrit-elasticsearch/src/test/java/com/google/gerrit/elasticsearch/ElasticContainer.java
@@ -45,7 +45,7 @@
       case V6_4:
         return "docker.elastic.co/elasticsearch/elasticsearch-oss:6.4.3";
       case V6_5:
-        return "docker.elastic.co/elasticsearch/elasticsearch-oss:6.5.3";
+        return "docker.elastic.co/elasticsearch/elasticsearch-oss:6.5.4";
       case V7_0:
         return "docker.elastic.co/elasticsearch/elasticsearch-oss:7.0.0-alpha1";
     }