slack: add prince213 to maintainers

+1
+1
pkgs/by-name/sl/slack/package.nix
··· 91 license = licenses.unfree; 92 maintainers = with maintainers; [ 93 mmahut 94 teutat3s 95 ]; 96 platforms = [
··· 91 license = licenses.unfree; 92 maintainers = with maintainers; [ 93 mmahut 94 + prince213 95 teutat3s 96 ]; 97 platforms = [