(Combined Sources)NMore than 50 Black leaders and organizations from across Massachusetts are pressing state lawmakers to act on a stalled police accountability bill. The Massachusetts House and Senate have approved separate versions of the bill. A conference committee has been working to hammer out a final version of the legislation. In a letter to lawmakers Friday, advocates say any final bill must have a series of components, including a strong Peace Officer Standards and Training system, limits on the use of force and limits to qualified immunity. Republican Gov. Charlie Baker said Thursday he looks forward to signing a bill once one reaches his desk.