6.9.0

Features

• Bump Flutter's min. supported version from 1.17.0 to 2.0.0 (#966)

This should not break anything since the Dart's min. version is already 2.12.0 and Flutter 2.0.0 uses Dart 2.12.0

Fixes

• Back compatibility of Object.hash for Dart 2.12.0 (#966)
• Fix back compatibility for OnErrorIntegration integration (#965)