ci: run full matrix testing, but only on push to main and release

.github/workflows/matrix-tests.yml

@@ -0,0 +1,28 @@
+# This matrix testing is for versions not already exercised by tests.yml
+# For regular pushes, we just test the baseline Python version, but when pushing
+# to main or release, we want to exercise the full matrix.
+name: Run Matrix Tests
+on:
+  push:
+    branches: [main, release]
+jobs:
+  test:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+        python-version: ["3.8", "3.9", "3.10", "3.11"]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v3
+      - uses: FedericoCarboni/setup-ffmpeg@v2
+        id: setup-ffmpeg
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install Python dependencies
+        run: |
+          pip install wheel
+          pip install -r requirements.txt -r requirements.dev.txt -r requirements.ci.txt -e .
+      - name: Run tests
+        run: cd test && python run.py prod