[feat][elixir] use elixir 1.18 built-in json module

[efcasado]

Description

A potential implementation for #21038.

Curious to hear your thoughts, @mrmstn.

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[mrmstn]

Hi @efcasado,

Nice! Thanks for submitting this PR—it looks good to me. I just want to run a quick test tomorrow to ensure it's as straightforward as it looks like 😄 .

@wing328 — Regarding versioning, this change doesn't technically break the client's API but does introduce a dependency on Elixir 1.18. Given that earlier versions are already EOL, my feeling is that it's safe to merge into master. However, I'm open to your thoughts—what's your take?

[wing328]

Given that earlier versions are already EOL, my feeling is that it's safe to merge into master. However, I'm open to your thoughts—what's your take?

sounds good to me too

users who need to use older versions of Elixir with the generated client can pin openapi generator to v7.12.0 without upgrading to newer versions that no longer support outdated Elixir versions

[mrmstn]

Just a quick update - looks like my nix environment still does not know elixir 1.18 - I'm currently figuring out on how to force the update since it's already available in 24.11 😅

[mrmstn]

LGTM