Tekton v1beta1 PipelineRun objects1 had the service account specified at the top level of spec, eg:
spec:
serviceAccountName: tack
However Tekton v1 PipelineRun objects have the service account inside a
taskRunTemplate object:
spec:
taskRunTemplate:
serviceAccountName: tack
This change properly places the service account name in the right place for Tekton v1 PipelineRun objects so that Tack can properly annotate CI pipelines.