change github to gitlab in readme

CONTRIBUTING.md

@@ -3,4 +3,4 @@ SPDX-FileCopyrightText: 2018 yuzu Emulator Project
 SPDX-License-Identifier: GPL-2.0-or-later
 -->
 
-**The Contributor's Guide has moved to [the yuzu wiki](https://github.com/yuzu-emu/yuzu/wiki/Contributing).**
+**The Contributor's Guide has moved to [the suyu wiki](https://gitlab.com/suyu2/suyu/-/wikis/Contributing).**