ci: release to pypi by tag push

Author: HiroIshida

.github/workflows/release.yaml

@@ -0,0 +1,26 @@
+name: Source Release
+
+on:
+   push:
+     tags:
+      - '[0-9]*'
+jobs:
+  pypi:
+    name: Release 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 publishing dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install pytest setuptools wheel twine scikit-build
+
+    - name: Build and publish
+      run: |
+        git submodule update --init
+        python setup.py sdist
+        twine upload --skip-existing -u __token__ -p ${{ secrets.PYPI_TOKEN }} dist/*