Update openr manifest to use main
Update openr manifest to use main

Summary: - Repo has a main branch now and not master

Reviewed By: xiangxu1121

Differential Revision: D31313971

fbshipit-source-id: 70d151e8a8632e296f25baf07ff9ac8348da7497

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift