Develop GitHub action to allow plugin developers to automatically upload plugin

Once CPM Hub was properly established, a GitHub action similar to the actions available for PyPi would allow developers to upload plugins as a workflow step. This would be done each time a new release is created:

```yaml
- name: Publish package
if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags')
uses: pypa/gh-action-pypi-publish@master
with:
user: __token__
password: ${{ secrets.pypi_password }}
```