Update zzz to Zig 0.15.2

[bernardassan]

Completed

• Fix building Zzz on Zig 0.15.2
• Update to use Tardy and Secsock that compiles on 0.15.2
• Fix Gzip compression
• Update Zzz to use std.Io.Writer
• Update CI to use Zig 0.15.2
• Fix example builds
• Update example in docs to 0.15.2
• Add hints on how to run fs and unix examples
• Use Result location types where possible
• initialize array types with @Splat
• Use a 8KiB buffer as max http header size by default

Tested all examples are working correctly and all test pass

Supersedes #58
Closes #58
Closes #57

Task

• update build.zig.zon when Update Supported Zig Version to 0.15.2 tardy#32 and Update secsock to zig 0.15.2 secsock#6 are merged