A 68-year-old man with a 40-year history of smoking and moderate COPD (post-bronchodilator FEV1 55 percent predicted) complains of daily dyspnoea limiting his ability to climb one flight of stairs. He has one exacerbation per year treated in the community. He currently uses short-acting salbutamol as needed only. According to the 2019 and 2023 Canadian Thoracic Society COPD pharmacotherapy updates, what is the most appropriate next pharmacologic step?