ci: fix flutter version on post-merge workflow

[Kirpal]

Description

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

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (a8d1f0e) compared to base (bc269cc).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #89   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           13        13           
  Lines          556       558    +2     
=========================================
+ Hits           556       558    +2     

Impacted Files	Coverage Δ
lib/src/blocked_text_image.dart	100.00% <100.00%> (ø)
lib/src/utilities.dart	100.00% <100.00%> (ø)

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