Change formatter from yapf to black

[kitagry]

yapf doesn't support python 3.10 syntax. So, I want to change formatter from yapf to black.

[hirosassa]

Thanks!
I think Black is a good choice of formatter, and I also think we should report yapf to follow the Python 3.10 syntax, too.
My recommendation is to report (I mean raise a issue) for this problem to yapf repo.
What do you think?

[kitagry]

The issue is already reported. e.x) google/yapf#1045

[yokomotod]

LGTM!

Great first step to switching formatter in the whole.

[hirosassa]

merged! thanks!