chore: use 2x faster black mirror (#68)

Committed via https://github.com/asottile/all-repos

Author: henryiii

.pre-commit-config.yaml

@@ -34,7 +34,7 @@ repos:
     exclude: ^doc/_static/.*.svg
 
 # Python formatting
-- repo: https://github.com/psf/black
+- repo: https://github.com/psf/black-pre-commit-mirror
   rev: 23.1.0
   hooks:
   - id: black