Build github plugin on stable-3.2 branch

Change-Id: I6b8a88452367a6e5222e2aaf36abb12b75354f5f
diff --git a/jenkins/gerrit-mvn-plugin-github.yaml b/jenkins/gerrit-mvn-plugin-github.yaml
index dd5e9f8..cd75d14 100644
--- a/jenkins/gerrit-mvn-plugin-github.yaml
+++ b/jenkins/gerrit-mvn-plugin-github.yaml
@@ -3,6 +3,7 @@
     repo: github
     branch:
       - master
+      - stable-3.2
       - stable-3.1
       - stable-3.0
       - stable-2.16