[pre-commit.ci] pre-commit autoupdate (#531)

updates:
- [github.com/psf/black: 23.7.0 → 23.9.1](psf/black@23.7.0...23.9.1)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

.pre-commit-config.yaml

@@ -2,7 +2,7 @@ ci:
   autoupdate_schedule: "monthly"
 repos:
 - repo: https://github.com/psf/black
-  rev: 23.7.0
+  rev: 23.9.1
   hooks:
   - id: black
     files: (^openff|^integration-tests)