chore: update pre-commit hooks (#518)

updates:
- [github.com/adamchainz/blacken-docs: 1.18.0 → 1.19.0](adamchainz/blacken-docs@1.18.0...1.19.0)

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

.pre-commit-config.yaml

@@ -50,7 +50,7 @@ repos:
         exclude: assets/js/webapp\.js
 
   - repo: https://github.com/adamchainz/blacken-docs
-    rev: 1.18.0
+    rev: 1.19.0
     hooks:
       - id: blacken-docs
         args: ["-E"]