Improve wheel install & smoke test in CI

Select the built wheel dynamically and echo its path, install the package via a file:// wheel URL including the [pytorch] extras and add PyTorch CPU index to pip, replace the multi-line import check with a single python -c import verification, and run dlclivegui --help in offscreen Qt mode. These changes make the smoke test more robust by ensuring PyTorch dependencies are resolved and exercising the CLI in a headless environment.

Author: C-Achard

.github/workflows/python-package.yml

@@ -67,12 +67,13 @@ jobs:
       # Smoke test: install the built wheel and verify the package imports
       - name: Install from wheel & smoke test
         run: |
-          python -m pip install dist/*.whl
-          python - <<'PY'
-          import importlib
-          m = importlib.import_module("dlclivegui")
-          print("Imported:", m.__name__)
-          PY
+          WHEEL=$(ls -1 dist/*.whl | head -n 1)
+          echo "Using wheel: $WHEEL"
+          python -m pip install \
+            --extra-index-url https://download.pytorch.org/whl/cpu \
+            "deeplabcut-live-gui[pytorch] @ file://$(pwd)/${WHEEL}"
+          python -c "import dlclivegui; print('Imported dlclivegui OK')"
+          QT_QPA_PLATFORM=offscreen dlclivegui --help
 
   build_release:
     # Tag-only build: produce the "official" release artifacts once matrix passed