Match system font

[vnghia]

Checklist

• [x] I am using the latest version - 1.4.3
• [x] I checked, but didn't find any duplicates (open OR closed) of this issue in the repo.
• [x] This issue contains only one feature request. I will open one issue for every feature I want to request.

Describe the feature you want

I think it would be nice if we could change the font of the app for a more consistent UI. Now I am using a custom system-wide font (thank to Magisk) and I think Koler should follow the system font instead of hard-coded the font. No need to add a custom font picker, follow the system font is good for me !

Additional context

I could contribute if you give me some pointers. Thank you very much !

How will you/everyone benefit from this feature?

It allows us to change the font, especially in custom rom where font could be changed in settings.