Add a TestPyPI OIDC rehearsal workflow as an alternative to #81

.github/workflows/testpypi.yml

@@ -0,0 +1,31 @@
+name: Publish to TestPyPI
+
+# Configure a TestPyPI Trusted Publisher for hsluv/hsluv-python, testpypi.yml,
+# environment testpypi. Run from main with a version not already on TestPyPI.
+on:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  id-token: write
+
+jobs:
+  publish:
+    if: github.repository == 'hsluv/hsluv-python' && github.ref == 'refs/heads/main'
+    runs-on: ubuntu-24.04
+    environment: testpypi
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1
+        with:
+          persist-credentials: false
+
+      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97
+        with:
+          python-version: '3.11'
+
+      - run: python -m pip install build
+      - run: python -m build
+
+      - uses: pypa/gh-action-pypi-publish@7245906fb61fa33a13554f9d5fb856fe61758086
+        with:
+          repository-url: https://test.pypi.org/legacy/