[pre-commit.ci] pre-commit autoupdate

updates:
- [github.com/psf/black: 21.4b2 → 21.5b1](psf/black@21.4b2...21.5b1)
- [github.com/PyCQA/flake8: 3.9.1 → 3.9.2](PyCQA/flake8@3.9.1...3.9.2)

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/psf/black
-    rev: 21.4b2
+    rev: 21.5b1
     hooks:
       - id: black
         args: ["--target-version=py36"]
@@ -12,7 +12,7 @@ repos:
         args: ["--target-version=py36"]
 
   - repo: https://github.com/PyCQA/flake8
-    rev: 3.9.1
+    rev: 3.9.2
     hooks:
       - id: flake8
         language_version: python3.8