[pre-commit.ci] pre-commit autoupdate (#172)

updates:
- [github.com/psf/black: 21.7b0 → 21.9b0](psf/black@21.7b0...21.9b0)
- [github.com/PyCQA/flake8: 3.9.2 → 4.0.1](PyCQA/flake8@3.9.2...4.0.1)

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

.pre-commit-config.yaml

@@ -15,10 +15,10 @@ repos:
             # excludes all the init files from sorting
             exclude: ^.*\/__init__\.py$
     -   repo: https://github.com/psf/black
-        rev: 21.7b0
+        rev: 21.9b0
         hooks:
         -   id: black
     -   repo: https://github.com/PyCQA/flake8
-        rev: 3.9.2
+        rev: 4.0.1
         hooks:
         -   id: flake8