Update Flow Builder and example

[robsonsilv4]

Status

READY

Breaking Changes

NO

Description

This PR updates Dart max constraint to <4.0.0, updates analysis_options and example project.

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)
• [x] 🧹 Code refactor
• [x] ✅ Build configuration change
• [ ] 📝 Documentation
• [x] 🗑️ Chore
• [x] 🧪 Testing

[robsonsilv4]

@felangel as promised, PR opened 🚀 Also updates PR #109

[felangel]

Thanks so much for taking the time to do this! This has already been addressed so closing 🙏