The Flutter screenshot article is out of date

[dkbast]

Describe the documentation update you'd like to see
The documentation for creating and uploading screenshots to the stores relies on golden_toolkit which has been discontinued. See https://pub.dev/packages/golden_toolkit

https://github.com/codemagic-ci-cd/codemagic-docs/edit/master/content/knowledge-codemagic/flutter-screenshots-stores.md

An alternative to goldens I'm currently investigating is using integration tests (which allows to get screenshots that contain native views like maps or web browsers).