add test.pypi.org upload step

Author: slayoo

.github/workflows/tests+artifacts.yml

@@ -84,3 +84,18 @@ jobs:
         name: dist
         path: dist
     - run: twine check --strict dist/*
+
+  dist_upload:
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags')
+    needs: [dist_check]
+    steps:
+    - uses: actions/download-artifact@v2
+      with:
+        name: dist
+        path: dist
+    - uses: pypa/gh-action-pypi-publish@master
+      with:
+        user: __token__
+        password: ${{ secrets.TEST_PYPI_API_TOKEN }}
+        repository_url: https://test.pypi.org/legacy/