Bump black from 25.1.0 to 25.9.0 in /requirements

Bumps [black](https://github.com/psf/black) from 25.1.0 to 25.9.0.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](psf/black@25.1.0...25.9.0)

---
updated-dependencies:
- dependency-name: black
  dependency-version: 25.9.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements/dev.txt

@@ -6,6 +6,6 @@ factory_boy==3.3.3
 Faker==37.8.0
 django-debug-toolbar==6.0.0
 pylint<3
-black==25.1.0
+black==25.9.0
 pre-commit==4.2.0
 fakeredis==2.31.3