Build reviewers plugin on stable-3.0

Change-Id: Iccbdbdb08c54ac1f6003f2aef271a616caec371b
diff --git a/jenkins/gerrit-buck-bazel-plugin-reviewers.yaml b/jenkins/gerrit-buck-bazel-plugin-reviewers.yaml
index 96874d5..0417247 100644
--- a/jenkins/gerrit-buck-bazel-plugin-reviewers.yaml
+++ b/jenkins/gerrit-buck-bazel-plugin-reviewers.yaml
@@ -7,6 +7,7 @@
       - 'plugin-{name}-bazel-{branch}':
           branch:
             - master
+            - stable-3.0
             - stable-2.16
             - stable-2.15
             - stable-2.14