introduce Ruff formatting

.github/workflows/format.yaml

@@ -0,0 +1,41 @@
+name: format
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - "**"
+    paths-ignore:
+      - "docs/**"
+
+concurrency:
+  group: build-format-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  ruff-format:
+    name: "Formatting checker"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.10"
+      - name: Setup virtual environment
+        run: |
+          python -m venv .venv
+      - name: Install development Python dependencies
+        run: |
+          source .venv/bin/activate
+          python -m pip install --upgrade pip
+          pip install -r dev-requirements.txt
+      - name: Ruff formatter
+        id: ruff
+        run: |
+          source .venv/bin/activate
+          ruff format --config line-length=100 --diff --exclude "*_pb2.py"