The Massachusetts House has approved Gov. Charlie Baker's plan to offer early retirement packages to thousands of state employees.The House voted 149-to-0 Wednesday afternoon, with three members voting present. The plan still needs Senate approval.The governor and lawmakers expect about 4,500 executive branch workers to take advantage of the program, saving the state about $173 million in the next fiscal year that starts on July 1. The savings estimate was about $5 million less than what Baker originally projected.Under the plan, state agencies would be allowed to "backfill" 20 percent of the salaries of the workers who opt for early retirement. That means the agencies could hire replacements for departing workers until they reached 20 percent of the salaries of the total salaries of those who left.