cherry-pick github workflow from #18 (without mypy)

Author: Martin Kirchgessner

.github/workflows/ci.yml

@@ -0,0 +1,101 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+    paths:
+      - '**.py'
+      - 'pyproject.toml'
+      - 'poetry.lock'
+      - '.github/workflows/ci.yml'
+  pull_request:
+    branches: [master]
+    paths:
+      - '**.py'
+      - 'pyproject.toml'
+      - 'poetry.lock'
+      - '.github/workflows/ci.yml'
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.14"
+
+      - name: Install Poetry
+        uses: snok/install-poetry@v1
+        with:
+          virtualenvs-create: true
+          virtualenvs-in-project: true
+
+      - name: Cache Poetry dependencies
+        uses: actions/cache@v4
+        with:
+          path: .venv
+          key: ${{ runner.os }}-python-3.14-poetry-${{ hashFiles('poetry.lock') }}
+
+      - name: Check for poetry file changes
+        id: filter
+        uses: dorny/paths-filter@v3
+        with:
+          filters: |
+            poetry:
+              - 'pyproject.toml'
+              - 'poetry.lock'
+
+      - name: Run poetry check
+        if: steps.filter.outputs.poetry == 'true'
+        run: poetry check --lock --strict
+
+      - name: Install dependencies
+        run: poetry install
+
+      - name: Run ruff check
+        run: poetry run ruff check .
+
+      - name: Run ruff format check
+        run: poetry run ruff format --check .
+
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0  # Required for diff-cover
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install Poetry
+        uses: snok/install-poetry@v1
+        with:
+          virtualenvs-create: true
+          virtualenvs-in-project: true
+
+      - name: Cache Poetry dependencies
+        uses: actions/cache@v4
+        with:
+          path: .venv
+          key: ${{ runner.os }}-python-${{ matrix.python-version }}-poetry-${{ hashFiles('poetry.lock') }}
+
+      - name: Install dependencies
+        run: poetry install
+
+      - name: Run tests with coverage
+        run: poetry run pytest
+
+      - name: Check coverage for new code
+        if: matrix.python-version == '3.14'
+        run: |
+          poetry run pip install diff-cover
+          poetry run diff-cover .reports/coverage.xml --compare-branch=origin/master --fail-under=100