Use Gerrit 2.16.17 in Dockerfile

Change-Id: I6c22ba52ec7ae4dc8234cb29314612a29ac93d9f
diff --git a/src/test/docker/gerrit/Dockerfile b/src/test/docker/gerrit/Dockerfile
index 2451bea..ec38c49 100644
--- a/src/test/docker/gerrit/Dockerfile
+++ b/src/test/docker/gerrit/Dockerfile
@@ -1,4 +1,4 @@
-FROM gerritcodereview/gerrit:2.16.16
+FROM gerritcodereview/gerrit:2.16.17
 
 ENV GERRIT_BRANCH=stable-2.16