Merge pull request #334 from jupyterhub/pre-commit-ci-update-config

[pre-commit.ci] pre-commit autoupdate

Author: consideRatio

.pre-commit-config.yaml

@@ -45,7 +45,7 @@ repos:
 
   # Autoformat: markdown, yaml, javascript (see the file .prettierignore)
   - repo: https://github.com/pre-commit/mirrors-prettier
-    rev: v3.0.3
+    rev: v4.0.0-alpha.8
     hooks:
       - id: prettier
         # FIXME: Autoformatting of our .js files is initially not enabled as it