[pre-commit.ci] pre-commit autoupdate (#658)

updates:
- [github.com/psf/black: 21.4b2 → 21.6b0](psf/black@21.4b2...21.6b0)
- [github.com/PyCQA/flake8: 3.9.1 → 3.9.2](PyCQA/flake8@3.9.1...3.9.2)
- [github.com/pre-commit/pre-commit-hooks: v3.4.0 → v4.0.1](pre-commit/pre-commit-hooks@v3.4.0...v4.0.1)

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

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/psf/black
-    rev: 21.4b2
+    rev: 21.6b0
     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
@@ -23,7 +23,7 @@ repos:
       - id: isort
 
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.4.0
+    rev: v4.0.1
     hooks:
       - id: trailing-whitespace
       - id: end-of-file-fixer