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)

_No response_

### 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.

The issue names no files, tests, or entry points. Start by locating the app's Taskwarrior integration and existing test or CI configuration, then determine how both Taskwarrior 2.x and 3.x can be exercised; done means continued testing covers both branches without breaking the mobile app.

Written by the indexing model from the issue text.