chore(shorebird_cli): deprecate accounts upgrade command

[felangel]

Description

• chore(shorebird_cli): deprecate accounts upgrade command

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

Patch coverage: 100.00% and no project coverage change.

Comparison is base (6764a2f) 100.00% compared to head (59c7ab6) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #933   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           78        78           
  Lines         2844      2847    +3     
=========================================
+ Hits          2844      2847    +3     

Files Changed	Coverage Δ
.../src/commands/account/upgrade_account_command.dart	100.00% <100.00%> (ø)

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