fix: prevent duplicate set-cookie headers

[wattanx]

🔗 Linked issue

Fixes: https://github.com/nuxt/bridge/issues/1272

❓ Type of change

• [ ] 📖 Documentation (updates to the documentation or readme)
• [x] 🐞 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

When useCookie is called more than once, it results in multiple set-cookie headers.

📝 Checklist

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

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commit: cd43e48