Add main branch in whitelist branches

Change-Id: If76a14ca88c39df6deeefe38127bbc71ba075644
diff --git a/jjb/airship/job_ipa_image_building_test.yml b/jjb/airship/job_ipa_image_building_test.yml
index a16ec00..10d8b52 100644
--- a/jjb/airship/job_ipa_image_building_test.yml
+++ b/jjb/airship/job_ipa_image_building_test.yml
@@ -131,6 +131,7 @@
         allow-whitelist-orgs-as-admins: True
         white-list-target-branches:
           - 'master'
+          - 'main'
         status-context: "test-ipa"
         success-status: "Passed"
         failure-status: "Failed"