Add PyPI publish action (#91)

* Add PyPI publish action

* Use poetry

* Bump version to 0.7.0

.github/workflows/pypi.yml

@@ -0,0 +1,33 @@
+name: PyPI Publish
+on: [push]
+
+jobs:
+  build:
+    name: Build and publish Python 🐍 distributions 📦 to PyPI
+    if: startsWith(github.ref, 'refs/tags')
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: Set up Python
+        uses: actions/setup-python@v1
+        with:
+          python-version: 3.9
+      - name: Install pypa/build
+        run: >-
+          python -m
+          pip install
+          build
+          --user
+      - name: Build a binary wheel and a source tarball
+        run: >-
+          python -m
+          build
+          --sdist
+          --wheel
+          --outdir dist/
+          .
+      - name: Publish package
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          user: __token__
+          password: ${{ secrets.PYPI_API_TOKEN }}