chore(retail): update package dependencies

[angelcaamal]

Description

Fixes #

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Checklist

• I have followed guidelines from CONTRIBUTING.MD and Samples Style Guide
• Tests pass: npm test (see Testing)
• Lint pass: npm run lint (see Style)
• Required CI tests pass (see CI testing)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This pull request is from a branch created directly off of GoogleCloudPlatform/nodejs-docs-samples. Not a fork.
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new sample directory, and I created GitHub Actions workflow for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

Note: Any check with (dev), (experimental), or (legacy) can be ignored and should not block your PR from merging (see CI testing).

[gemini-code-assist]

Code Review

This pull request updates the Node.js engine requirement to >=20.0.0, removes a duplicate engines block, and upgrades several dependencies and devDependencies in retail/package.json. A critical issue was identified with upgrading chai to v6.0.0, as Chai v5 and above are ESM-only and will cause tests to fail in this CommonJS project. It is recommended to keep chai at ^4.5.0 to maintain compatibility.

[gemini-code-assist]

Chai v5 and above are ESM-only. Since this project uses CommonJS (require), upgrading to chai v6.0.0 will cause tests to fail with ERR_REQUIRE_ESM. It is recommended to keep chai at ^4.5.0 to maintain compatibility.

Suggested change

	"chai": "^6.0.0",
	"chai": "^4.5.0",