Add pre commit config

.pre-commit-config.yaml

+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v3.2.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+  - repo: https://github.com/asottile/reorder_python_imports
+    rev: v2.5.0
+    hooks:
+      - id: reorder-python-imports
+  - repo: https://github.com/psf/black
+    rev: 21.5b0
+    hooks:
+      - id: black
+  - repo: https://github.com/pycqa/flake8
+    rev: 3.9.1
+    hooks:
+      - id: flake8