chore(shorebird_cli): don't allow iOS releases to be created with Flutter < 3.19.5

[bryanoltman]

Description

Disallow iOS releasing with Flutter <3.19.5 to prepare for 1.0.

Fixes #1863

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 100.00%. Comparing base (4f221a5) to head (a5447fa).
Report is 1 commits behind head on main.

❗ Current head a5447fa differs from pull request most recent head 993a2b7. Consider uploading reports for the commit 993a2b7 to get more accurate results

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1864   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          173       173           
  Lines         5488      5497    +9     
=========================================
+ Hits          5488      5497    +9     

Flag	Coverage Δ
shorebird_cli	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.