[pre-commit.ci] pre-commit autoupdate (#670)

updates:
- [github.com/asottile/blacken-docs: 1.16.0 → 1.18.0](adamchainz/blacken-docs@1.16.0...1.18.0)

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

.pre-commit-config.yaml

@@ -29,7 +29,7 @@ repos:
     hooks:
       - id: add-trailing-comma
   - repo: https://github.com/asottile/blacken-docs
-    rev: 1.16.0
+    rev: 1.18.0
     hooks:
       - id: blacken-docs