Switch base of /e/OS Tasks
- /e/ version: 1.8.1-s-20230203257059-stable-FP4
- Device model(s): Fairphone 4
## Summary
[OpenTasks](https://github.com/dmfs/opentasks), the current base of the /e/OS Tasks app, seemed to be not longer maintained.
## Description
**What is the current behavior?**
The actual /e/OS Tasks app maybe wouldn't get any updates (bugfixes, improments, ...) from the upstream project any more.
**What is the improved behavior?**
There should be an switch to another opensource tasks app, which is maintained.
Suggestion (with openTasks for comparison) - feel free to add any further suggestion and functional requirements
| name | repo link | calDAV | recurrence |
| ---- | --------- | ------ | ---------- |
| OpenTasks | https://github.com/dmfs/opentasks | :white_check_mark: (via DAVx5) | :x: |
| tasks | https://github.com/tasks/tasks | :white_check_mark: (via DAVx5 and standalone) | :white_check_mark: (not with DAVx5) |
| jtx Board | https://github.com/TechbeeAT/jtxBoard | :white_check_mark: (via DAVx5) | :white_check_mark: |
**What does it bring?**
An maintained upstream project have many benefits. For example security fixes and new features.
## Mock-ups
<Provide a mock-up of how it would look with the improvement>
## Examples
The support of recurrence tasks would be an direct benefit for all users.
## Validation
<List test case that will be run to validate that the issue is working as expected>
issue