[pre-commit.ci] pre-commit autoupdate

updates:
- [github.com/psf/black: 21.9b0 → 21.10b0](psf/black@21.9b0...21.10b0)
- [github.com/PyCQA/flake8: 3.9.2 → 4.0.1](PyCQA/flake8@3.9.2...4.0.1)

.pre-commit-config.yaml

@@ -3,14 +3,14 @@ default_language_version:
 
 repos:
 -   repo: https://github.com/psf/black
-    rev: 21.9b0
+    rev: 21.10b0
     hooks:
     - id: black
       pass_filenames: true
       args: ["--config", "backend-project/pyproject.toml"]
       exclude: "migrations/"
 -   repo: https://github.com/PyCQA/flake8
-    rev: 3.9.2
+    rev: 4.0.1
     hooks:
     - id: flake8
       pass_filenames: true