[BUG] For python3.8 and python3.9, dooit cannot startup normally.

[Weissle]

Describe the bug 🐛
Met error when using python3.8 or 3.9 to run dooit.

To Reproduce 🐣
Steps to reproduce the behavior:

1. Use python3.8 or python3.9.
2. Under the root of dooit, python main.py

Expected behavior 🤔
dooit starts up normally.

Screenshots 🧐
For python3.8

Traceback (most recent call last):
  File "main.py", line 1, in <module>
    from dooit.__init__ import main
  File "/home/weissle/learn/dooit/dooit/__init__.py", line 3, in <module>
    from .ui.tui import Dooit
  File "/home/weissle/learn/dooit/dooit/ui/tui.py", line 4, in <module>
    from dooit.utils.watcher import Watcher
  File "/home/weissle/learn/dooit/dooit/utils/__init__.py", line 4, in <module>
    from .keybinder import KeyBinder
  File "/home/weissle/learn/dooit/dooit/utils/keybinder.py", line 57, in <module>
    configured_keys = DEFAULTS | configured_keys
TypeError: unsupported operand type(s) for |: 'dict' and 'dict'

For python3.9

Traceback (most recent call last):
  File "/home/weissle/learn/dooit/main.py", line 1, in <module>
    from dooit.__init__ import main
  File "/home/weissle/learn/dooit/dooit/__init__.py", line 3, in <module>
    from .ui.tui import Dooit
  File "/home/weissle/learn/dooit/dooit/ui/tui.py", line 6, in <module>
    from dooit.ui.widgets import WorkspaceTree, TodoTree, StatusBar, HelpScreen
  File "/home/weissle/learn/dooit/dooit/ui/widgets/__init__.py", line 2, in <module>
    from .sort_options import SortOptions
  File "/home/weissle/learn/dooit/dooit/ui/widgets/sort_options.py", line 14, in <module>
    class SortOptions(Widget):
  File "/home/weissle/learn/dooit/dooit/ui/widgets/sort_options.py", line 23, in SortOptions
    name: str | None = None,
TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'

Desktop (please complete the following information): 🤖

• OS: WSL
• Version Ubuntu 20.03

Additional context 📝

[kraanzu]

I see. Thanks for the PR! I thought that the match statements were the only thing keeping it from running on lower versions of python 😕

Would you like to work on this @Weissle ?

[Weissle]

Will take a look when I have time.