Brian Cox, John Malkovich, Harry Hamlin and Nathalie Emmanuel will lend their voices to “Unsinkable,” a new historical fiction podcast created by Misha Crosby and John Mawson slated to premiere July 10 on Wondery+, TheWrap has learned. The series tells the true story of the San Demetrio — one of the most extraordinary tales of heroism, fortitude and seamanship of …