fix: prismic unsplash image proxy

[lihbr]

🔗 Linked issue

Resolves: #1600

❓ 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)
• ✨ 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

Some images distributed through Prismic are images directly served by Unsplash's CDN. This PR takes that into account within the Prismic provider to redirect Unsplash images to the Unsplash provider.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.93%. Comparing base (d2e4eb0) to head (a609f24).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1614      +/-   ##
==========================================
- Coverage   62.98%   62.93%   -0.06%     
==========================================
  Files          79       79              
  Lines        3534     3529       -5     
  Branches      406      407       +1     
==========================================
- Hits         2226     2221       -5     
  Misses       1279     1279              
  Partials       29       29              

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[Baroshem]

Amazing work @lihbr !