refactor: move httpmock and serde_json to dev-dependencies

[joaolfp]

✨ Summary

• move httpmock and serde_json from regular dependencies to [dev-dependencies] in Cargo.toml
• update Cargo.lock with minor version bumps (async-lock 3.4.1 → 3.4.2, typenum 1.19.0 → 1.20.0)

🔧 Type of Change

• ✨ Enhancement
• 🐞 Bug fix
• 🔐 Security fix
• 💥 Breaking change
• 🚀 New feature
• 📦 New release
• 📚 Documentation
• ♻️ Refactor

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Note

Low Risk
Low risk dependency-scope change that should only affect build/test compilation; runtime code paths are unchanged aside from minor indirect crate bumps via Cargo.lock.

Overview
Moves httpmock and serde_json out of main [dependencies] into [dev-dependencies], reducing the release build dependency set.

Regenerates Cargo.lock, picking up small indirect updates (async-lock 3.4.1→3.4.2, typenum 1.19.0→1.20.0).

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[github-actions]

🎉 All unit tests passed! ✅

[gemini-code-assist]

Code Review

This pull request updates the versions of async-lock and typenum in Cargo.lock. Additionally, it moves httpmock and serde_json from the main dependencies to dev-dependencies in Cargo.toml. I have no feedback to provide.