chore: add workflow to test trusted publisher

Author: paketeserrano

.github/workflows/publish-testpypi-manual.yml

@@ -0,0 +1,23 @@
+name: publish-testpypi-manual
+
+on:
+  workflow_dispatch: {}   # run manually from the Actions tab
+
+permissions:
+  contents: read
+  id-token: write         # required for PyPI/TestPyPI Trusted Publishers (OIDC)
+
+jobs:
+  testpypi:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065
+      # build artifacts (wheel + sdist)
+      - run: python -m pip install --upgrade build
+      - run: python -m build
+      # publish to **TestPyPI** via Trusted Publishers (OIDC)
+      - uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          repository-url: https://test.pypi.org/legacy/
+          skip-existing: true