By James Mackenzie ZAPORIZHZHIA, Ukraine (Reuters) – The Red Cross was renewing efforts to evacuate civilians in a convoy from the besieged port of Mariupol on Saturday as Russian forces looked to be regrouping for fresh attacks in southeast Ukraine. Encircled since the early days of Russia’s five-week old invasion, Mariupol has been Moscow’s main target in Ukraine’s southeastern region of Donbas. Tens of thousands of civilians are trapped there with scant access to food and water. The International Committee of the Red Cross (ICRC) sent a team on Friday to lead a convoy of about 54 Ukrainian …