Add deadsnakes jobs

Author: YannickJadoul

.github/workflows/ci.yml

@@ -165,6 +165,51 @@ jobs:
       run: pytest tests/extra_setuptools
 
 
+  deadsnakes:
+    strategy:
+      fail-fast: false
+      matrix:
+        python:
+        - version: 2.7
+          debug: true
+        - version: 3.9
+          debug: true
+        - version: 3.10-dev
+          debug: false
+
+    name: "🐍 ${{ matrix.python.version }} (deadsnakes)${{ matrix.python.debug && ' • Debug' || '' }}"
+    runs-on: ubuntu-lates
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Setup Python ${{ matrix.python.version }}
+      uses: deadsnakes/[email protected]
+      with:
+        python-version: ${{ matrix.python.version }}
+        debug: ${{ matrix.python.version.debug }}
+
+    - name: Prepare env
+      run: python -m pip install -r tests/requirements.txt --prefer-binary
+
+    - name: Configure
+      run: >
+        cmake -S . -B build
+        -DPYBIND11_WERROR=ON
+        -DDOWNLOAD_CATCH=ON
+        -DDOWNLOAD_EIGEN=ON
+        -DCMAKE_CXX_STANDARD=17
+
+    - name: Build
+      run: cmake --build build -j 2
+
+    - name: Python tests
+      run: cmake --build build --target pytest
+
+    - name: C++ tests
+      run: cmake --build build --target cpptest
+
+
   # Testing on clang using the excellent silkeh clang docker images
   clang:
     runs-on: ubuntu-latest