LeetCode CN Contest not working

[YingChenLiu18]

Hello, the contest function of Leetcode Cn is not working.

[JacobLinCool]

The APIs for LeetCode and LeetCode CN were previously different, which caused the contest extension not to work for LeetCode CN. However, I haven't looked into the LeetCode CN API for a long time; maybe they have been merged into one now.

I'll investigate this.