PHILADELPHIA — When Philadelphia Black clergy members held a forum last week with Pennsylvania’s U.S. Senate candidates, there was one notable absence: the Democratic front-runner. Lt. Gov. John Fetterman didn’t attend. His three main primary opponents did, answering policy questions the night after Martin Luther King Jr. Day at the historic Enon Tabernacle Baptist Church in Germantown. The event was streamed live by churches in Philadelphia and Pittsburgh as candidates addressed concerns raised by Black leaders, whose communities are a pillar of the Democratic coalition. Fetterman said he had…