🐍 Ensure support for Python 3.12/3.8/3.7

The README claims that Python 3.7 or higher is required,
so I believe it would be nice to ensure that all 3.7+
versions are actually supported by enabling testing
against them on CI.

These changes also:
  - add coverage reporting
  - disable the fail-fast mode for tests
  - make CI use pipx to install poetry
  - make CI use pytest to run tests
  - force colors on CI
  - bump actions/checkout to v4
  - bump actions/setup-python to v5

.github/workflows/codeql-analysis.yml

@@ -16,7 +16,7 @@ jobs:
 
  steps:
  - name: Checkout repository
- uses: actions/checkout@v2
+ uses: actions/checkout@v4
  with:
  # We must fetch at least the immediate parents so that if this is
  # a pull request then we can check out the head.

.github/workflows/test.yml

@@ -14,22 +14,34 @@ on:
  - ".github/workflows/test.yml"
  - "**.py"
 
+env:
+ FORCE_COLOR: '1'
+
 jobs:
  test:
  strategy:
+ fail-fast: false
  matrix:
- python: ["3.9", "3.10", "3.11"]
+ python:
+ - "3.12"
+ - "3.11"
+ - "3.10"
+ - "3.9"
+ - "3.8"
+ - "3.7"
  runs-on: ubuntu-latest
  steps:
- - uses: actions/checkout@v3
- - uses: actions/setup-python@v4
+ - uses: actions/checkout@v4
+ - uses: actions/setup-python@v5
  with:
  python-version: ${{ matrix.python }}
  - name: Setup Graphviz
  uses: ts-graphviz/setup-graphviz@v1
  - name: Install poetry
- run: curl -sSL https://install.python-poetry.org | python3 -
- - name: Run all tests
  run: |
- poetry install
- poetry run python -m unittest -v tests/*.py
+ pipx install poetry
+ poetry env use ${{ matrix.python }}
+ - name: Install dependencies
+ run: poetry install
+ - name: Run all tests
+ run: poetry run pytest