fix: 0.13.0-dev.68+b86c4bde6 compatibility

[ert78gb]

Summary:

• use std.fs.cwd().writeFile instead of deprecated std.fs.cwd().writeFile2
• rename the members of the new std.posix.iovec_const
• bump minimum_zig_version 0.13.0-dev.33+8af59d1f9 => 0.13.0-dev.68+b86c4bde6

[ert78gb]

if I see well one part of this PR covered by #1877

[mochalins]

The minimum Zig version here is incorrect. New iovec field names were not yet introduced here.

[ert78gb]

it was introduced in the master. I recognised the LLVM 18 CI issue after I opened the PR. If I see well they are actively working on LLVM. I am keeping my eyes on the zig releases and I will update the PR when the new release will available.

[mochalins]

it was introduced in the master. I recognised the LLVM 18 CI issue after I opened the PR. If I see well they are actively working on LLVM. I am keeping my eyes on the zig releases and I will update the PR when the new release will available.

Generally I believe it is best practice for the PR to actually contain the versions necessary for the patch, regardless of whether it is yet available on upstream download links. Regardless, newer Zig versions are now available to the CI.

[ert78gb]

I updated theminimum_zig_version let me know if I should update something else.