Add pre-commit hook to run black, flake8 & isort

.pre-commit-config.yaml

@@ -0,0 +1,13 @@
+repos:
+  - repo: https://github.com/psf/black
+    rev: 22.1.0
+    hooks:
+    - id: black
+  - repo: https://github.com/PyCQA/isort
+    rev: 5.9.3
+    hooks:
+      - id: isort
+  - repo: https://github.com/PyCQA/flake8
+    rev: 4.0.1
+    hooks:
+      - id: flake8

pyproject.toml

@@ -0,0 +1,6 @@
+[tool.black]
+skip-string-normalization = true
+target-version = ['py38']
+
+[tool.isort]
+multi_line_output = 4

tox.ini

@@ -0,0 +1,10 @@
+[flake8]
+count = True
+exclude =
+    migrations
+    resources   # exclude code that will be deprecated
+    tests   # exclude code that will be deprecated
+max-complexity = 10
+max-line-length = 120
+show-source = True
+statistics = True