CI: Reintroduce publishing to Test PyPI

This time only for non-release changes though.

Signed-off-by: Stephen Finucane <stephen@that.guru>

Author: stephenfin

.github/workflows/ci.yaml

@@ -78,6 +78,12 @@ jobs:
         run: python -m pip install build
       - name: Build a binary wheel and a source tarball
         run: python -m build --sdist --wheel --outdir dist/ .
+      - name: Publish distribution to Test PyPI
+        if: ${{ ! startsWith(github.ref, 'refs/tags') }}
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          password: ${{ secrets.TEST_PYPI_API_TOKEN }}
+          repository_url: https://test.pypi.org/legacy/
       - name: Publish distribution to PyPI
         if: startsWith(github.ref, 'refs/tags')
         uses: pypa/gh-action-pypi-publish@release/v1