Add a GitHub Actions CI workflow

Signed-off-by: Michał Górny <mgorny@gentoo.org>

Author: mgorny

.github/workflows/ci.yaml

@@ -0,0 +1,25 @@
+name: CI
+on: [push, pull_request]
+jobs:
+  build:
+    strategy:
+      matrix:
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11.0-beta - 3.11",
+                         "pypy-3.7", "pypy-3.8", "pypy-3.9"]
+      fail-fast: false
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install pytest
+        run: pip install pytest
+      - name: Autoreconf
+        run: autoreconf -vi
+      - name: Configure
+        run: ./configure -C --with-python-impls="python3.10"
+      - name: Distcheck
+        run: make -j$(nproc) distcheck