Update black requirement from ~=23.7.0 to ~=23.9.1

Updates the requirements on [black](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@23.7.0...23.9.1)

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

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

requirements.dev.txt

@@ -1,4 +1,4 @@
 anyio~=3.7.0
-black~=23.7.0
+black~=23.9.1
 pytest~=7.4.0
 pytest-mock~=3.11.1