Updated version to 1.2.0 and libraries, and updated changelog.

[matux]

Description of the change

• This updates the final changelog and the Rollbar Flutter SDK version to 1.2.0, including two libraries to their latest versions.
• This PR makes the new SDK version ready to publish.
• This PR also fixes some versioning issues with sqlite3 that would break the CI.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Maintenance
• New release

Related issues

• Address 120026

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer