zlib doesnt build

[Jaap Aart]

Dear,

While trying to build zlib from gsrc (or really gcc-13 which requires 
zlib), I stumbled onto a broken (404) link: 
https://www.zlib.net/zlib-1.2.13.tar.xz.
This can be fixed when patching the makefile to use use 
https://github.com/madler/zlib/releases/download/v1.2.13/zlib-1.2.13.tar.xz.
I cannot find any xz files on the zlib.net website, only .gz.

Kind Regards,

Jaap Aarts