Fix the new GPA description website url.

[travischen0219]

The origin url is already not found. So I find a new one url to replace it. Thanks for you calculator, it helps me a lot!

From 成大資工110學弟

[ctxhou]

hey @travischen0219 ! 太感謝你幫忙修正啦！如果有想要新增/精進的功能也歡迎提出 PR