add action to publish on tag

Author: willforde

.github/workflows/tests.yml

@@ -49,3 +49,13 @@ jobs:
 
       - name: Test linting with flake8
         run: flake8 --max-line-length=127
+
+  publish:
+    runs-on: ubuntu-latest
+    needs: [tests, linting]
+    steps:
+      - name: Publish package
+        if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          password: ${{ secrets.PYPI_API_TOKEN }}