Add workflow to publish to PyPI

Along with the existing workflow that can publish to
Test PyPI, this change also adds official PyPI.

The difference is that this workflow will only publish
if the commit is tagged.

Signed-off-by: Eric Brown <browne@vmware.com>

.github/workflows/publish-to-pypi.yml

@@ -0,0 +1,29 @@
+name: Publish to PyPI
+
+on: workflow_dispatch
+
+jobs:
+  build-n-publish:
+    name: Build and publish to PyPI
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - name: Set up Python 3.7
+      uses: actions/setup-python@v2
+      with:
+        python-version: 3.7
+
+    - name: Install dependencies
+      run: pip install wheel
+
+    - name: Build a binary wheel and a source tarball
+      run: |
+        python setup.py sdist bdist_wheel
+
+    - name: Publish distribution to PyPI
+      if: startsWith(github.ref, 'refs/tags')
+      uses: pypa/gh-action-pypi-publish@master
+      with:
+        password: ${{ secrets.pypi_password }}