Added new workflow to publish the Python package to PyPi upon release.

Author: baochunli

.github/workflows/pypi_publish.yml

@@ -0,0 +1,31 @@
+# This workflows will upload a Python Package using Twine when a release is created.
+
+name: Upload the Plato Python Package to PyPI
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: "3.x"
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install --upgrade setuptools wheel twine
+      - name: Build and publish
+        env:
+          TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
+          TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
+        run: |
+          rm -rf dist/
+          pip wheel . -w dist
+          twine upload --repository testpypi dist/plato_learn*
+          twine upload --repository pypi dist/plato_learn*