batch: Add stable-3.0 and stable-3.1 branches

Change-Id: I84eb821442ad37986b114cd60df2062667508795
diff --git a/jenkins/gerrit-bazel-plugin-batch.yaml b/jenkins/gerrit-bazel-plugin-batch.yaml
index d55f5e2..82cf443 100644
--- a/jenkins/gerrit-bazel-plugin-batch.yaml
+++ b/jenkins/gerrit-bazel-plugin-batch.yaml
@@ -4,4 +4,6 @@
       - 'plugin-{name}-bazel-{branch}':
           branch:
             - master
+            - stable-3.1
+            - stable-3.0
             - stable-2.16