Add github action to publish to PyPI

[MartinHjelmare]

Breaking change

Proposed change

• This action will publish to PyPI when creating a GitHub release.
• To make it work we need to set a GitHub secret called PYPI_TOKEN, with a valid PyPI token that can publish releases for the project.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New service (thank you!)
• New feature (which adds functionality to an existing service)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests
• Documentation or code sample

Example of code:

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated to README