Build stable-3.0 branch of messageoftheday plugin

Change-Id: I8b7d1e185ff50115d912c96fc3157573113b0c24
diff --git a/jenkins/gerrit-bazel-plugin-messageoftheday.yaml b/jenkins/gerrit-bazel-plugin-messageoftheday.yaml
index d20572e..0eb90ac 100644
--- a/jenkins/gerrit-bazel-plugin-messageoftheday.yaml
+++ b/jenkins/gerrit-bazel-plugin-messageoftheday.yaml
@@ -4,4 +4,5 @@
       - 'plugin-{name}-bazel-{branch}':
           branch:
             - master
+            - stable-3.0
             - stable-2.16