STY: enforce Python formatting

Author: davidesarra

.github/workflows/lint.yml

@@ -0,0 +1,22 @@
+name: Lint
+on:
+  push:
+    branches:
+      - "*"
+  pull_request:
+    branches:
+      - master
+jobs:
+  python_formatting_check:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Setup Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: 3.8
+    - name: Checkout repository
+      uses: actions/checkout@v2
+    - name: Install dev dependencies
+      run: pip install -r requirements/dev_requirements.txt
+    - name: Check that Python files are formatted correctly
+      run: black --check --diff .