Use Gerrit 3.0.9 in Dockerfile

Change-Id: Ib859cd78b69e988e0c3fdf4f346ce7cc13b1ef16

src/test/docker/gerrit/Dockerfile

diff --git a/src/test/docker/gerrit/Dockerfile b/src/test/docker/gerrit/Dockerfile
index b5c7b31..0dc189d 100644
--- a/src/test/docker/gerrit/Dockerfile
+++ b/src/test/docker/gerrit/Dockerfile
@@ -1,4 +1,4 @@
-FROM gerritcodereview/gerrit:3.0.8
+FROM gerritcodereview/gerrit:3.0.9
 
 ENV GERRIT_BRANCH=stable-3.0