fix(types): allow narrowing of the method option in NitroFetchOptions

[dsluijk]

🔗 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

This PR allows you to enhance the Nitro fetch method by providing this in a generic.

This change is needed to allow nuxt/nuxt#15280 to be fixed.

📝 Checklist

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

[codecov]

Codecov Report

Merging #883 (ac4c489) into main (6596c5f) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #883      +/-   ##
==========================================
+ Coverage   67.47%   67.50%   +0.03%     
==========================================
  Files          59       59              
  Lines        5860     5866       +6     
  Branches      635      637       +2     
==========================================
+ Hits         3954     3960       +6     
  Misses       1897     1897              
  Partials        9        9              

Impacted Files	Coverage Δ
src/types/fetch.ts	100.00% <100.00%> (ø)
src/prerender.ts	89.34% <0.00%> (+0.14%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[pi0]

Thanks all!