Build its-base on Gerrit v3.0

Change-Id: I33b28967c7e6989b263feb6cf25dbeb4eff5e9f6
diff --git a/jenkins/gerrit-buck-bazel-plugin-its-base.yaml b/jenkins/gerrit-buck-bazel-plugin-its-base.yaml
index dda423a..fd9eacb 100644
--- a/jenkins/gerrit-buck-bazel-plugin-its-base.yaml
+++ b/jenkins/gerrit-buck-bazel-plugin-its-base.yaml
@@ -7,6 +7,7 @@
       - 'plugin-{name}-bazel-{branch}':
           branch:
             - master
+            - stable-3.0
             - stable-2.16
             - stable-2.15
             - stable-2.14