Kanban-python

- Update minimum python version in ci test

- Update Docs with pipx link

- Fix datetime for test for dict creation
- Amount of completed task to tasks of current year in report

- Add `from __future__ import annotations` to controls.py to not error on Union TypeHint if python version is <=3.9

- Add `Due_Date` to Task Structure
- App now asks for `Due_Date` on task creation and task update
- Show `days left` on board for task with `Due_Date`
- Show `days left` of most overdue or urgent task for each board when changing boards
- Add `freezegun` as test requirement

- Bug Fix, `Complete_Time`-Key was wrong in Task Creation, when task was created with `kanban scan`
- Add new function `kanban report` to show a github contribution like visual + creating a `.md` report
- The report is created in a `kanban_report` folder next to the `kanban_boards` folder
- Updated Readme/Docs accordingly