fix(shorebird_cli): close input stream when extracting cache artifacts

[bryanoltman]

Description

Possibly the cause of the e2e failures in https://github.com/shorebirdtech/shorebird/actions/runs/8725954542/job/23940129912

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.85%. Comparing base (0fec75d) to head (d42c064).

Additional details and impacted files

@@             Coverage Diff              @@
##              main    #1923       +/-   ##
============================================
- Coverage   100.00%   87.85%   -12.15%     
============================================
  Files          174      174               
  Lines         5503     5500        -3     
============================================
- Hits          5503     4832      -671     
- Misses           0      668      +668     

Flag	Coverage Δ
shorebird_cli	84.33% <100.00%> (-15.67%)	⬇️

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