GitHub.DistributedTask.ObjectTemplating.TemplateValidationException: The template is not valid. nationalarchives/ds-docker-actions/main/.github/actions/remove-untagged/action.yml (Line: 30, Col: 7): Unexpected value 'shell'
at GitHub.DistributedTask.ObjectTemplating.TemplateValidationErrors.Check()
at GitHub.Runner.Worker.ActionManifestManager.ConvertRuns(IExecutionContext executionContext, TemplateContext templateContext, TemplateToken inputsToken, String fileRelativePath, MappingToken outputs)
at GitHub.Runner.Worker.ActionManifestManager.Load(IExecutionContext executionContext, String manifestFile)