W A S H I N G T O N, April 6 — The good news for consumers is gas prices are anticipated to drop this summer. But the bad news is the decline will be slow. With an increase in international oil production as a backdrop, the Energy Department today dramatically revised its forecast for summer gasoline prices. The agency said prices should peak later this month and begin dropping sometime in May, averaging about $1.46 a gallon throughout the summer. Even Cheaper Fall Prices And there’s even more good news: Gasoline prices may dip lower still ....