Added the ability to max your weapon maintenance rank

[simon-wg]

I've tried this out, and it works well on my machine.

The issue is that entries are not created until the weapon has been used at least once and gotten some xp. However it works otherwise.

[simon-wg]

Alright, now mypy appears to be happy, I'm thinking that since there's a few pr:s open right now that we can wait with the formatting so we don't get too many unneccessary merge conflicts.

[wahlp]

ran into an error trying to run on python 3.9.6

Traceback (most recent call last):
  File "C:\xxx\DRG-Save-Editor\src\main\python\main.py", line 521, in <module>
    def get_weapons(save_data) -> dict[int, list[int | bool]]:
TypeError: unsupported operand type(s) for |: 'type' and 'type'

and then after removing the above type hint

Traceback (most recent call last):
  File "C:\xxx\DRG-Save-Editor\src\main\python\main.py", line 1239, in <module>
    weapon_stats: dict[int, list[int, int, bool]] | None = None # type: ignore
TypeError: unsupported operand type(s) for |: 'types.GenericAlias' and 'NoneType'

keeping this would narrow supported versions only to 3.10

other than that, works as expected. all weapons were maxxed out, apart from an unlocked weapon with 0 xp.

[AnthonyMichaelTDM]

this is likely going to be the last merge before 1.9 gets released, so I'm going to use it to resolve some flake8 lints and whatnot aswell