Bump black from 24.10.0 to 26.3.1 in /example_isort_formatting_plugin

Bumps [black](https://github.com/psf/black) from 24.10.0 to 26.3.1.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](https://github.com/psf/black/compare/24.10.0...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>