Update black[jupyter] requirement from ~=26.3.0 to ~=26.3.1

Updates the requirements on [black[jupyter]](https://github.com/psf/black) to permit the latest version.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](psf/black@26.3.0...26.3.1)

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

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

Author: dependabot[bot]

requirements.txt

@@ -6,7 +6,7 @@ dash~=3.4.0
 pytest~=9.0.2
 pylint~=4.0.5
 black~=26.3.1
-black[jupyter]~=26.3.0
+black[jupyter]~=26.3.1
 pyodbc~=5.3.0
 numpy~=2.4.3
 gov-uk-dashboards~=28.4.0