fix: uppercase windows drive letters

[danielroe]

🔗 Linked issue

resolves nuxt/nuxt#24621

❓ 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 was possible for a path segment to mismatch (c: !== C:) owing to drive letter case. This normalises it in relative before splitting into segments.

I can update this if #142 merges first.

📝 Checklist

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c9029e2) 99.41% compared to head (5a518f2) 99.42%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #151   +/-   ##
=======================================
  Coverage   99.41%   99.42%           
=======================================
  Files           4        4           
  Lines         342      346    +4     
  Branches      105      106    +1     
=======================================
+ Hits          340      344    +4     
  Misses          2        2           

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