[pre-commit.ci] pre-commit autoupdate (#920)

updates:
- [github.com/keewis/blackdoc: v0.3.8 → v0.3.9](keewis/blackdoc@v0.3.8...v0.3.9)

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

.pre-commit-config.yaml

@@ -43,7 +43,7 @@ repos:
     args: ["--in-place", "--make-summary-multi-line", "--pre-summary-newline"]
 
 - repo: https://github.com/keewis/blackdoc
-  rev: v0.3.8
+  rev: v0.3.9
   hooks:
   - id: blackdoc