build(deps): bump black from 26.1.0 to 26.3.1

Bumps [black](https://github.com/psf/black) from 26.1.0 to 26.3.1.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](psf/black@26.1.0...26.3.1)

---
updated-dependencies:
- dependency-name: black
  dependency-version: 26.3.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -3,7 +3,7 @@ SQLAlchemy==2.0.48
 annotated-doc==0.0.4
 annotated-types==0.7.0
 anyio==4.12.1
-black==26.1.0
+black==26.3.1
 certifi==2026.2.25
 click==8.3.1
 exceptiongroup==1.3.1