add black config, pre-commit and github action

Author: bouttier

.github/workflows/black.yml

@@ -0,0 +1,10 @@
+name: Lint
+
+on: [push, pull_request]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: psf/black@stable

.pre-commit-config.yaml

@@ -0,0 +1,6 @@
+repos:
+  - repo: https://github.com/psf/black
+    rev: 22.6.0
+    hooks:
+      - id: black
+        language_version: python3.9

pyproject.toml

@@ -12,3 +12,6 @@ omit = [
     "*/tests/*",
     "*/migrations/*",
 ]
+
+[tool.black]
+line-length = 99