Change download links

[cvalka4]

Windows users should be directed to https://github.com/M2Team/NanaZip
OS X users should be directed to https://www.keka.io/en/

[PopuriAO29]

For those anyone who had 7-Zip Installed, you still able install that such as NanaZip (for Windows users) and for macOS users is keka. Therefore, I'm going to say it as Oppose this.

[win98se]

uselessshit.org is much shittier than all three tools (the original 7-Zip, NanaZip, Keka; even if Keka is paid that makes it not good) mentioned here.