ci: Fix Python 2.7 build

.github/workflows/ci.yml

@@ -11,9 +11,20 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
-      - uses: actions/setup-python@v4
+      # 2.7 not on setup-python: https://github.com/actions/setup-python/issues/672
+      - if: matrix.py_version != '2.7'
+        uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
+      - name: Set up Python 2.7
+        if: matrix.py_version == '2.7'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y python2.7 python2.7-dev python2-pip-whl
+          sudo ln -sf python2.7 /usr/bin/python
+          export PYTHONPATH=$(echo /usr/share/python-wheels/pip-*py2*.whl)
+          sudo --preserve-env=PYTHONPATH python -m pip install --upgrade pip setuptools wheel
+          sudo chown -R "$USER" /usr/local/lib/python2.7
       - run: python --version
 
       - run: pip install -U pip