Automates release publishing and finalization

[MelbourneDeveloper]

TLDR;

This pull request automates the release publishing process using GitHub Actions. It streamlines the process of creating release branches, updating dependencies, and creating pull requests.

What Does This Do?

• Creates a new workflow to finalize the release, switching dependencies back to local ones after publishing.
• Modifies the publish workflow to prepare the release branch and create a pull request to main.
• Removes publish_to: none from pubspec.yaml files.

Brief Details?

• The "Finalize Release" workflow is triggered after the "Publish Tier 3" workflow completes successfully. It checks out the release branch, switches dependencies to local, commits, and pushes the changes.
• The "Publish Release" workflow now validates that the tag is on main, extracts the version from the tag, creates a release branch, switches to pub.dev dependencies, commits and pushes the changes, and creates a pull request to main. The pull request body contains instructions to not merge until publishing is complete.
• The workflows now use the setup action to setup Dart.

How Do The Tests Prove The Change Works?

There are no specific tests included in this pull request, but the workflows themselves serve as integration tests, ensuring that the release process is automated and functions as expected.