Run nox -s test on GitHub actions

.github/workflows/tests.yml

@@ -0,0 +1,24 @@
+name: tests
+on: push
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
+    name: test-${{ matrix.python-version }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+          architecture: x64
+
+      - run: python --version
+      - run: pip --version
+
+      # The following pinned dependencies must be updated manually
+      - run: pip install nox==2024.4.15
+      - run: pip install poetry==1.8.3
+
+      - run: nox -s test-${{ matrix.python-version }}

README.md

@@ -8,6 +8,7 @@ The goal of the `lalib` project is to create
     by reading and writing code.
 
 
+[![Test suite: Status](https://github.com/webartifex/lalib/actions/workflows/tests.yml/badge.svg)](https://github.com/webartifex/lalib/actions/workflows/tests.yml)
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 [![Type checking: mypy](https://www.mypy-lang.org/static/mypy_badge.svg)](https://mypy-lang.org/)
 [![Code linting: ruff](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/charliermarsh/ruff/main/assets/badge/v2.json)](https://github.com/astral-sh/ruff)