MARIUPOL, Ukraine (Reuters) – Dozens of Ukrainian fighters, some apparently unwounded, surrendered on Tuesday after weeks holed up in the bunkers and tunnels below Mariupol’s Azovstal steel works as the most devastating siege of Russia’s war in Ukraine drew to a close. Russian forces pummelled Mariupol, a major port on the Sea of Azov between Russia and Crimea, with artillery for weeks while some of the fiercest urban warfare of the conflict left much of the city a wasteland. Civilians and hundreds of Ukrainian fighters, many of them from the Azov Regiment, sought refuge in the Azovstal works,…