CI: add GitHub Actions workflow for running tests with pytest

.github/workflows/python-test.yml

@@ -0,0 +1,20 @@
+name: Pytest
+
+on:
+  push:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup PDM
+        uses: pdm-project/setup-pdm@v4
+      - name: Install dependencies
+        run: pdm install
+      - name: Test with pytest
+        run: |
+          pytest