add publish workflow

Signed-off-by: Matthew Peveler <matt.peveler@gmail.com>

.github/workflows/publish.yml

@@ -0,0 +1,23 @@
+name: Publish 🐍s
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Python 3.7
+        uses: actions/setup-python@v1
+        with:
+          python-version: 3.7
+
+      - run: python setup.py sdist bdist_wheel
+
+      - name: Publish to PyPI
+        uses: pypa/gh-action-pypi-publish@master
+        with:
+          password: ${{ secrets.PYPI_TOKEN }}