GitHub.DistributedTask.ObjectTemplating.TemplateValidationException: The template is not valid. /Users/runner/work/flutter-action/flutter-action/./action.yaml (Line: 79, Col: 7): Required property is missing: 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)