[lint] bump black to >=25

Summary:
This is the yearly bumping for the black linter. Note that v25.x still supports python 3.9
See D15374 for the previous bump.

But this time it is probably the last bump, as this is an intermediate step before replacing black with ruff. This helps making the ruff diff smaller by fixing some differences in advance.

Test Plan:

arc liberate
arc lint --everything

ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D18903