CI: Update publishing workflow

Use PyPA's new "Trusted Publisher" thing:
https://docs.pypi.org/trusted-publishers/

Fixes #49

.github/workflows/python_publish.yml

@@ -1,27 +1,26 @@
 name: Upload Python Package
 
 on:
-  # Only run when a release is created
   release:
-    types: [created]
+    types: [published]
 
 jobs:
   deploy:
     runs-on: ubuntu-latest
+    permissions:
+      # IMPORTANT: this permission is mandatory for trusted publishing
+      id-token: write
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v3
       - name: Set up Python
-        uses: actions/setup-python@v1
+        uses: actions/setup-python@v4
         with:
-          python-version: "3.x"
+          python-version: '3.x'
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install setuptools wheel twine
-      - name: Build and publish
-        env:
-          TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
-          TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
-        run: |
-          python setup.py sdist bdist_wheel
-          twine upload dist/*
+          pip install build
+      - name: Build package
+        run: python -m build --sdist --wheel
+      - name: Publish package
+        uses: pypa/gh-action-pypi-publish@release/v1