[pre-commit.ci] pre-commit autoupdate (#17)

updates:
- [github.com/psf/black: 21.8b0 → 21.9b0](psf/black@21.8b0...21.9b0)
- [github.com/pre-commit/mirrors-prettier: v2.4.0 → v2.4.1](pre-commit/mirrors-prettier@v2.4.0...v2.4.1)

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

Author: pre-commit-ci[bot]

.pre-commit-config.yaml

@@ -10,7 +10,7 @@ repos:
       - id: double-quote-string-fixer
 
   - repo: https://github.com/psf/black
-    rev: 21.8b0
+    rev: 21.9b0
     hooks:
       - id: black
 
@@ -34,6 +34,6 @@ repos:
       - id: isort
 
   - repo: https://github.com/pre-commit/mirrors-prettier
-    rev: v2.4.0
+    rev: v2.4.1
     hooks:
       - id: prettier