fix: append set-cookie headers in web reponse

[Hebilicious]

🔗 Linked issue

Hebilicious/authjs-nuxt#38

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 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)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

It's possible that a Header object has multiple "set-cookie" headers.

📝 Checklist

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

[codecov]

Codecov Report

Merging #453 (6442ee6) into main (0968902) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##             main     #453   +/-   ##
=======================================
  Coverage   77.76%   77.76%           
=======================================
  Files          26       26           
  Lines        2698     2698           
  Branches      399      399           
=======================================
  Hits         2098     2098           
  Misses        600      600           

Impacted Files	Coverage Δ
src/utils/response.ts	69.73% <0.00%> (ø)