some general code care

[hoba87]

no functional changes, only

• sorting imports
• replacing deprecated distutils.version
• loosening matplotlib and kivy requirements
• pytest deprectation warnings only for this package

[AndreMiras]

I have nothing against code formatters like black or isort, but then should it not be part of the repo & CI.
That way we know what formatter was used, what ruling and we are sure things don't get messed up with on the next pull requests?

[hoba87]

I have added isort and black configuration settings and according changes of code formatting

[AndreMiras]

Thanks for looking this up 💪
This is more changes than I initially expected after introducing the formatter.
I don't have anything against black myself as I use for my personal projects, but I know it's a contentious topic in Kivy.
So I wanted to let the PR open a little bit to see if anyone would chime in.
Tehn I saw some of the recent commit from misl6 was actually running black (7864a8e), so I guess we're good.
After merging that PR, it could be nice to have a follow up for adding format checks from the CI

[AndreMiras]

LGTM