Add github action to publish to PyPI (#370)

.github/workflows/publish.yml

@@ -0,0 +1,27 @@
+name: Publish releases to PyPI
+
+on:
+  release:
+    types: [published, prereleased]
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2.4.0
+      - name: Set up Python 3.6
+        uses: actions/setup-python@v2.3.2
+        with:
+          python-version: 3.6
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install wheel
+      - name: Build
+        run: |
+          python setup.py sdist bdist_wheel
+      - name: Publish release to PyPI
+        uses: pypa/gh-action-pypi-publish@v1.5.0
+        with:
+          user: __token__
+          password: ${{ secrets.PYPI_TOKEN }}