Use deaksnakes to test on multiple debug versions of CPython

.github/workflows/ci.yml

@@ -58,30 +58,30 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
+        python-version: ['3.9', '3.8', '3.7']
 
     steps:
       - uses: actions/checkout@v2
 
-      - name: Install Python
-        run: sudo apt install python3-dbg python3-dev python3-setuptools
+      - name: Set up Python from deadsnakes
+        uses: deadsnakes/[email protected]
+        with:
+          python-version: ${{ matrix.python-version }}
+          debug: true
 
       - name: Check Python debug build
-        run: python3-dbg -c "import sys; print(hasattr(sys, 'gettotalrefcount'))"
-
-      - name: Check Python version
-        run: python3-dbg --version
+        run: python -c "import sys; print(hasattr(sys, 'gettotalrefcount'))"
 
       - name: Install/Upgrade Python dependencies
-        run: python3 -m pip install --upgrade pip wheel
+        run: python -m pip install --upgrade pip wheel
 
       - name: Build
-        run: python3-dbg -m pip install .
+        run: python -m pip install .
 
       - name: Run tests
         run: |
-          python3 -m pip install pytest pytest-xdist
-          python3-dbg -m pytest -n auto test/
-
+          python -m pip install pytest pytest-xdist
+          python -m pytest -n auto test/
 
   poc_tests:
     name: Proof of concept tests