Build ref-prottection plugn in 3.3

Change-Id: I413366eafbbb160a820adb69e41e262d2f61f429
diff --git a/jenkins/gerrit-bazel-plugin-ref-protection.yaml b/jenkins/gerrit-bazel-plugin-ref-protection.yaml
index eb97986..2ccf4d4 100644
--- a/jenkins/gerrit-bazel-plugin-ref-protection.yaml
+++ b/jenkins/gerrit-bazel-plugin-ref-protection.yaml
@@ -7,6 +7,7 @@
           gerrit-branch:
             - master
             - stable-3.2
+            - stable-3.3
       - 'plugin-{name}-bazel-{branch}':
           branch:
             - stable-3.1