Build menuextender against gerrit 3.3

Change-Id: Ib97c38a3ab96b70d01dcea822d56e03e6657a4ad
diff --git a/jenkins/gerrit-bazel-plugin-menuextender.yaml b/jenkins/gerrit-bazel-plugin-menuextender.yaml
index 84cb54d..c32bacc 100644
--- a/jenkins/gerrit-bazel-plugin-menuextender.yaml
+++ b/jenkins/gerrit-bazel-plugin-menuextender.yaml
@@ -6,6 +6,7 @@
             - master
           gerrit-branch:
             - master
+            - stable-3.3
             - stable-3.2
             - stable-3.1
             - stable-2.16