Support Null-Safety
Support Null-Safety (#30) * Support Null-Safety (#28) Co-authored-by: Minh Đức * Update CHANGELOG.md (#29) Co-authored-by: Minh Đức * Bump 2.0.0-nullsafety.1 version * Add repository info to pubspec.yaml * Add publish_to: 'none' to example * Bump version 2.0.0 Co-authored-by: Minh Đức <ducnm31@onemount.com>