add pre-commit config for flake8

.pre-commit-config.yaml

@@ -3,3 +3,14 @@ repos:
     rev: 19.3b0
     hooks:
       - id: black
+  - repo: https://gitlab.com/pycqa/flake8
+    rev: 3.7.7
+    hooks:
+      - id: flake8
+        additional_dependencies: [flake8-bugbear]
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.1.0
+    hooks:
+      - id: check-byte-order-marker
+      - id: trailing-whitespace
+      - id: end-of-file-fixer