- API change to add new `github` provider field in `GitRepository` spec.
- Controller change to use the GitHub authentication information specified in `.spec.secretRef` to create the auth options to authenticate to git repositories when the `provider` field is set to `github`,
- Tests for new `github` provider field
- Updated docs to use GitHub Apps for authentication in source-controller.
Signed-off-by: Dipti Pai <diptipai89@outlook.com>