Upgrade zlib_version on AppVeyor
They removed https://zlib.net/zlib1212.zip because https://zlib.net/zlib1213.zip was released :thinking_face:
Fix CI failures like: https://ci.appveyor.com/project/ruby/ruby/builds/45064876/job/bb9biogolh0u2595
Added by k0kubun (Takashi Kokubun) about 3 years ago
Upgrade zlib_version on AppVeyor
They removed https://zlib.net/zlib1212.zip because
https://zlib.net/zlib1213.zip was released :thinking_face:
Fix CI failures like:
https://ci.appveyor.com/project/ruby/ruby/builds/45064876/job/bb9biogolh0u2595