add a publishing CI (#27)

Author: keewis

.github/workflows/publish.yaml

@@ -0,0 +1,32 @@
+name: Upload package to PyPI
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  publish:
+    name: Publish to PyPI
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python
+        uses: actions/setup-python@v1
+        with:
+          python-version: '3.x'
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip build twine
+      - name: Build
+        run: |
+          python -m build --sdist --wheel --outdir dist/ .
+      - name: Check the built archives
+        run: |
+          twine check dist/*
+      - name: Publish to PyPI
+        uses: pypa/gh-action-pypi-publish@54b39fb9371c0b3a6f9f14bb8a67394defc7a806
+        with:
+          user: __token__
+          password: ${{ secrets.pypi_token }}
+          repository_url: https://upload.pypi.org/legacy/
+          verify_metadata: true