refactor: in line with other code, change the indentation to 2 spaces.

[wattanx]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

In the process of outputting the manifest, other code uses JSON.stringify(json, null, 2) to stringify. Therefore, I changed it to match other code by using JSON.stringify(json, null, 2).

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.