Update release action for trusted publishing

Author: elinscott

.github/workflows/release.yml

@@ -15,6 +15,11 @@ jobs:
     name: Publish koopmans
     runs-on: ubuntu-latest
     if: github.repository == 'epfl-theos/koopmans' && startsWith(github.ref, 'refs/tags/v')
+    environment:
+      name: pypi
+      url: https://pypi.org/p/koopmans
+    permissions:
+      id-token: write  # IMPORTANT: this permission is mandatory for trusted publishing
 
     steps:
     - name: Checkout repository
@@ -36,6 +41,3 @@ jobs:
 
     - name: Publish package to PyPI
       uses: pypa/gh-action-pypi-publish@release/v1
-      with:
-        user: __token__
-        password: ${{ secrets.PYPI_API_TOKEN }}