ci: use a trusted publisher token for publishing to PyPI

.github/workflows/publish.yml

@@ -14,6 +14,8 @@ jobs:
   build-n-publish:
     name: Build and Publish to PyPI
     runs-on: ubuntu-latest
+    permissions:
+      id-token: write
     needs: [framework-tests, observability-charm-tests, hello-charm-tests]
     steps:
       - uses: actions/checkout@v3
@@ -27,5 +29,3 @@ jobs:
         run: python setup.py sdist bdist_wheel
       - name: Publish
         uses: pypa/gh-action-pypi-publish@release/v1
-        with:
-          password: ${{ secrets.PYPI_API_TOKEN }}

.github/workflows/test-publish.yml

@@ -0,0 +1,30 @@
+name: Test Publishing
+on: [workflow_dispatch, workflow_call]
+
+jobs:
+  framework-tests:
+    uses: ./.github/workflows/framework-tests.yaml
+  observability-charm-tests:
+    uses: ./.github/workflows/observability-charm-tests.yaml
+  hello-charm-tests:
+    uses: ./.github/workflows/hello-charm-tests.yaml
+  build-n-publish:
+    name: Build and Publish to PyPI
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+    needs: [framework-tests, observability-charm-tests, hello-charm-tests]
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup Python
+        uses: actions/setup-python@v1
+        with:
+          python-version: "3.10"
+      - name: Install wheel
+        run: pip install wheel
+      - name: Build
+        run: python setup.py sdist bdist_wheel
+      - name: Publish to test.pypi.org
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          repository-url: https://test.pypi.org/legacy/