Update black and pre-commit config

.pre-commit-config.yaml

@@ -3,8 +3,7 @@ repos:
     rev: stable
     hooks:
       - id: black
-        language_version: python3.6
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v1.3.0
+    rev: v2.3.0
     hooks:
       - id: flake8

pyproject.toml

 [tool.black]
-py36 = true
+target_version = ['py37']