Json: set allow_duplicate_key in JSON.parse call

[samford]

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brew livecheck querious is producing a warning in reference to the JSON.parse call in livecheck's Json.parse_json method: 'warning: detected duplicate key "prerelease" in JSON object. This will raise an error in json 3.0 unless enabled via allow_duplicate_key: true at line 1 column 1'. We don't have any control over upstream JSON data, so this adds an allow_duplicate_key: true option to the JSON.parse call to resolve this issue and maintain the current behavior.

[Copilot]

Pull request overview

This PR updates Homebrew livecheck’s JSON strategy to preserve current parsing behavior when upstream JSON contains duplicate keys, avoiding warnings now and preventing failures with newer json versions.

Changes:

• Passes allow_duplicate_key: true to JSON.parse in Livecheck::Strategy::Json.parse_json.

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[MikeMcQuaid]

Looks good, thanks!