Wholesale inflation picked up last month after cooling earlier this summer as higher oil and gas prices stemming from the Iran war are keeping costs elevated. The Labor Department’s producer price index — which captures inflation before it reaches consumers — rose 5.4% in August from a year ago, up from 4.7% in July, the government said Thursday. Inflation has shown some signs of easing in recent months but is still high, frustrating consumers who are struggling with more expensive gas, groceries, clothing and other essentials. Oil prices globally topped $100 a barrel this week on renewed fighting in the Middle East.