A law that barred publisher Rupert Murdoch from continuing to own television stations and newspapers in the same city was struck down Tuesday as unconstitutional by a federal appeals court. The divided panel of the U.S. Circuit Court of Appeals in Washington voided a provision passed by Congress late last year that would force Murdoch to sell the Boston Herald or WFXT-TV in that city by June 30 to comply with rules that forbid single ownership of a newspaper and a television station in one city. The 2-1 court decision does not affect Murdoch's $37 million sale of the New York Post to real estate developer Peter Kalikow, a deal that was spurred by the law's enactment.