Language code changes over time: zh_CN -> zh_Hans

[Jean-Baptiste]

Thank for your answers, I don't debate Weblate can use the old code.

I see two issues:
1. depending on the target platform, upstream project have to manually convert language code used by the system
2. The default setting in a translation platform is for every project, it force every user project we host to remain on the old code by default

Short term solution is use old codes and I could have done it without telling anyone.

But I feel like we need to have upstream support for new languages code so we follow the standards evolution over time. Android did the change years ago, Django also, Microsoft. Net also, and I'm sure we can find other example.

I'm confused on the reason why we have zh_Hans_CN in Locales folder, does it means we can use it already?