Rep. Matt Gaetz (R-FL) has been served a subpoena stemming from a civil lawsuit over accusations that he had sex with an underage girl, sources told ABC News Thursday. The subpoena demands Gaetz sit for a deposition to discuss allegations stemming from a years-long Justice Department investigation into allegations that he had sex with a 17-year-old girl, who is now in her 20s, according to the report. Lobbyist Chris Dorworth, a friend of Gaetz’s, filed the defamation and racketeering lawsuit against the young woman, but the subpoena comes from her attorneys, the report notes. Gaetz has publicl…