feat: upgrade to Dart 3.12

[marcossevilla]

Description

Bump Dart SDK to version 3.12

Requirements

• All CI/CD checks are passing.
• There is no drop in the test coverage percentage.

Additional Context

No response

[unicoderbot]

Great, I will work on a PR and push it soon.

• Preparing environment
  • Cloning repository
  • Setting up dev environment
• Working on changes
• Reviewing changes
• Opening pull request

I've opened a pull request: #152