Bump black from 21.7b0 to 24.3.0 in /python

Bumps [black](https://github.com/psf/black) from 21.7b0 to 24.3.0.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](https://github.com/psf/black/commits/24.3.0)

---
updated-dependencies:
- dependency-name: black
  dependency-type: direct:development
...

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

python/requirements-dev.txt

@@ -1,5 +1,5 @@
 # Test and linters
-black==21.7b0
+black==24.3.0
 coverage==5.4              # 2nd lvl dep on cov required to avoid sqllite dep
 flake8==5.0.4
 grpcio-tools==1.37.1