recipe_bundler: use refs/heads/main Change-Id: Ifa48875c54c846613bde4e6de07746d960618185 Bug: b:200859048 Reviewed-on: https://chromium-review.googlesource.com/c/codecs/infra/+/3243980 Reviewed-by: Bharath Chandra Elluru <[email protected]> Commit-Queue: Roberto Alanis Baez <[email protected]>