Continue support for taskwarrior 2.x as well as 3.x

### Describe your improvement idea or feature request

Taskwarrior development towards 3.x is great, but many of us are still going to be using task 2.x because of database changes, regressions, etc., so I am hoping that taskwarrior-flutter development and testing does not leave the 2.x branch behind. Thanks

### How would you like to see it implemented?

continued testing on the 2.x AND 3.x branches

### Put here any screenshots or videos (optional)

_No response_

### How can we contact you (optional)

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### Would you like to work on this issue?

None

### By submitting this issue, I have confirmed that:

- [X] I have starred the repo ⭐ and watched 👀 it on GitHub and followed the contribution guidelines.

L’issue ne nomme aucun fichier, test ou point d’entrée. Commencez par localiser l’intégration de Taskwarrior de l’application et la configuration existante des tests ou de CI, puis déterminez comment exercer à la fois Taskwarrior 2.x et 3.x ; le travail est considéré comme terminé lorsque les tests continus couvrent les deux branches sans casser l’application mobile.

Rédigé par le modèle d'indexation à partir du texte de l'issue.