Hello @sne_envidan,
We’re aware of the problem with GitHub action. Here you can find a temporary workaround and explanation: Dart: support Melos dependency management? - #7 by Margarita_Nedzelska
We will improve the onboarding and will think about how we can improve the Sonar GitHub action. Meanwhile, have a look at the provided workaround and let us know if this fixes your issue.
Best,
Margarita