portfolio-filemanager: add chuangzhu as a maintainer

pkgs/applications/file-managers/portfolio-filemanager/default.nix

···
     changelog = "https://github.com/tchx84/Portfolio/blob/v${version}/CHANGELOG.md";
     license = licenses.gpl3Plus;
     platforms = platforms.linux;
-    maintainers = with maintainers; [ dotlambda ];
+    maintainers = with maintainers; [ dotlambda chuangzhu ];
   };
 }