Bump black from 22.10.0 to 24.3.0 in /requirements

Bumps [black](https://github.com/psf/black) from 22.10.0 to 24.3.0.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](psf/black@22.10.0...24.3.0)

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

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

requirements/testing.txt

@@ -9,7 +9,7 @@ flake8>=5.0.4,<8
 #  Don't change this version without running CI builds;
 #  The latest version may not be available for older Python runtime
 black>=22.8.0; python_version=="3.6"
-black==22.10.0; python_version>"3.6"
+black==24.3.0; python_version>"3.6"
 click==8.0.4  # black is affected by https://github.com/pallets/click/issues/2225
 psutil>=5,<6
 #  used only under slack_sdk/*_store