feat: add zeabur provider

[yuaanlin]

🔗 Linked issue

nitrojs/nitro#1942

❓ 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

Adding a new provider for Zeabur

In the CI/CD environment of Zeabur, there is a environment variable ZEABUR=1 can be used to detect the provider.

📝 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 (e1bfb39) 85.04% compared to head (9b9204c) 85.13%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #93      +/-   ##
==========================================
+ Coverage   85.04%   85.13%   +0.09%     
==========================================
  Files           7        7              
  Lines         321      323       +2     
  Branches       30       30              
==========================================
+ Hits          273      275       +2     
  Misses         45       45              
  Partials        3        3              

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