Metal3: Change branch for dev-tools master -> main

Change-Id: I9fe77779d055290a0cb4972f6822b27a7565284e
diff --git a/jjb/metal3/job_openstack_image_building.yml b/jjb/metal3/job_openstack_image_building.yml
index 05eec4e..8860cd4 100644
--- a/jjb/metal3/job_openstack_image_building.yml
+++ b/jjb/metal3/job_openstack_image_building.yml
@@ -58,7 +58,7 @@
           url: "{ci_github_repo}"
           credentials-id: "{ci_github_jenkins_credentials_id}"
           branches:
-            - 'master'
+            - 'main'
           name: 'origin'
           refspec: '+refs/heads/*:refs/remotes/origin/*'
           wipe-workspace: True