ci: sign pypi packages (#1392)

Signed-off-by: Michele Dolfi <dol@zurich.ibm.com>

.github/workflows/pypi.yml

@@ -14,8 +14,17 @@ env:
 jobs:
   build-and-publish:
     runs-on: ubuntu-latest
+    environment:
+      name: pypi
+      url: https://pypi.org/p/docling
+    permissions:
+      id-token: write  # IMPORTANT: mandatory for trusted publishing
     steps:
       - uses: actions/checkout@v4
       - uses: ./.github/actions/setup-poetry
       - name: Build and publish
-        run: poetry publish --build --no-interaction --username=__token__ --password=${{ secrets.PYPI_TOKEN }}
+        run: poetry build
+      - name: Publish distribution 📦 to PyPI
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          attestations: true