updateWorkflow method
Update workflow
Implementation
@override
Future<Workflow> updateWorkflow(Workflow workflow) async {
if (!_workflows.containsKey(workflow.id)) {
throw ArgumentError('Workflow not found');
}
final updatedWorkflow = workflow.copyWith(updatedAt: DateTime.now());
_workflows[updatedWorkflow.id] = updatedWorkflow;
return updatedWorkflow;
}