publish on GH release

[dulmandakh]

Proposed changes

This PR make it possible to automatically publish the package to PyPI on GH release, release tag must start with v, for example v3.4.0, and will use tag name (excluding v) as version number.

You must to set PYPI_USERNAME and PYPI_PASSWORD variables in secrets to work.

It's based on my experience working on https://github.com/react-native-community/docker-android/blob/master/.github/workflows/publish.yml and https://docs.github.com/en/free-pro-team@latest/actions/guides/building-and-testing-python#publishing-to-package-registries.

@omab please review and merge

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (PEP8, lint, formatting, renaming, etc)
• Refactoring (no functional changes, no api changes)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Build related changes (build process, tests runner, etc)
• [x ] Other (please describe): publish package to PyPI

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• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works

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[omab]

I've introduced a release workflow that does this work and also:

1. Checks that the tag properly matches the release version in the module
2. Verifies that long descriptions will render properly on pypi (using twine)
3. Publishes the artifacts
4. Uses the token based authentication (no need to have my personal creds in the secrets, just a token)
5. Uses Python 3.9

[dulmandakh]

@omab good to see you back. I would like to contribute to the project.

[omab]

Thanks @dulmandakh. Please take a look to #539 about contributing if you are interested in a maintainer position.