[pre-commit.ci] pre-commit autoupdate

updates:
- [github.com/psf/black: 21.7b0 → 21.8b0](psf/black@21.7b0...21.8b0)
- [github.com/asottile/blacken-docs: v1.10.0 → v1.11.0](adamchainz/blacken-docs@v1.10.0...v1.11.0)

.pre-commit-config.yaml

@@ -33,13 +33,13 @@ repos:
   - id: isort
 
 - repo: https://github.com/psf/black
-  rev: 21.7b0
+  rev: 21.8b0
   hooks:
   - id: black
     language_version: python3
 
 - repo: https://github.com/asottile/blacken-docs
-  rev: v1.10.0
+  rev: v1.11.0
   hooks:
   - id: blacken-docs
     additional_dependencies: [black]